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Çift GaAlAs/GaAs ve GaInAs/GaAs kuantum kuyularının kuyu genişliğine bağlı olarak elektronik özellikleri
(Sivas Cumhuriyet University, 2019) Ozturk, Ozan; Ozturk, Emine; Elagoz, Sezai
Bu çalışmada, çift Ga1-x Alx As/GaAs kuantum kuyularının (A yapısı) ve Ga1-x Inx As/GaAs /GaAs kuantum kuyularının (B yapısı) elektronik özellikleri kuyu genişliğine bağlı olarak incelenmiştir. Etkin kütle yaklaşımı kullanılarak, Schrödinger denkleminin çözümüyle enerji seviyeleri, dalga fonksiyonları ve bu sistemin olasılık yoğunlukları hesaplanmıştır. Elde edilen sonuçlara göre, A ve B yapısının temel farklılıkları yasak enerji aralığı ve etkili kütledir. A yapısı için engel GaAlAs ve kuyu GaAs’dır. B yapısı için ise engel GaAs ve kuyu GaInAs’dır. Ayrıca, A yapısının potansiyel yüksekliği ve enerji seviyeleri her zaman B yapısından düşüktür. Kuyu genişliği, çift kuantum kuyusunun (DQW) elektronik özellikleri üzerinde büyük bir etkiye sahiptir. Bu özellikler, ayarlanabilir yarı iletken cihazların tasarımı için pratik bir ilgiye sahiptir.
Comparison of asymmetric double parabolic-inversed parabolic quantum wells for linear optical (1-2) transition
(ELSEVIER GMBH, URBAN & FISCHER VERLAG, 2017) Ozturk, Emine
In present study, for asymmetric double parabolic quantum well (ADPQW) and asymmetric double inverse parabolic quantum well (ADIPQW) the linear optical absorption (OA) coefficient, the linear refractive index change (RIC), resonant peaks of the linear OA and the optical rectification (OR) coefficients are examined as dependent on the structural parameters (barrier width (b) and Al concentration at the well center (sigma)). The results display that the variation of all OA and OR coefficients and RIC depend on b and sigma-parameter. I have also shown that the cc-parameter has a significant effect on the electronic and optical properties of ADPQW and ADIPQW, and that the energy levels and the dipole moment matrix elements vary depending on the shape of the limiting potential. The intersubband absorption spectrum in the ADPQW shows the blue shift by increasing the b and cc values. Whereas the absorption spectrum for ADIPQW shows blue shift for sigma = 1 with increasing b-values, this spectrum shows red shifts for sigma = 5. The electro-optic properties of these structures promise many potential applications in high speed spatial light modulators and switches. So, it can be adjusted RIC and the resonant peak size of the linear OA and OR coefficient by changing Al density at the well center in addition to the barrier dimensions. (C) 2017 Elsevier GmbH. All rights reserved.
Comparison of Ga1-xAlxAs/GaAs and Ga(1-x)ln(x)As/GaAs quantum wells as dependent on Al and In concentrations under intense laser field
(WORLD SCIENTIFIC PUBL CO PTE LTD, 2015) Ozturk, Emine
In this study, the electronic properties of Ga1-xAlxAs/GaAs and Ga(1-x)ln(x)As/GaAs quantum wells (QWs) are theoretically calculated as dependent on the intense laser field (ILF) and x-concentration value within the effective mass approximation and the envelope function approach. Our results show that the shape of confined potential profile, the energy differences and the dipole moment matrix elements are changed as dependent on the ILF and x-value. The energy levels of different QWs give different values by increasing ILF amplitudes and x-concentrations. In the case of QW under ILF, there are significant modifications of the electrical states of QWs, due to the effects of confining the potential resulting from the applied ILF. I say that the variation of Ga1-xAlxAs/GaAs QW under ILF is more than Ga1-xInxAs/GaAs QW. The numerical results show that the structure parameters have a great effect on the electronic characteristics of these QW structures.
Depending on the electric and magnetic field of the linear optical absorption and rectification coefficient in triple quantum well
(SPRINGER, 2017) Ozturk, Emine
In this study, the alteration of the potential profile, the energy levels, the dipole matrix element and the resonant peaks of the linear optical absorption (OA) and optical rectification (OR) coefficients in GaAs/GaAlAs triple quantum well (TQW) are calculated as dependent on the applied electric field and the magnetic field. The results show that the shape of confined potential profile, the energy levels and the dipole moment matrix elements are changed as dependent on the external fields. Also, the resonant peaks of the OA and OR coefficients depend on the applied external field effects. Therefore, I hope that these results will provide important improvement in semiconductor device applications, for suitable choice of electric and magnetic field values. It may particularly be useful in technological applications that the structure of TQW changes with the strength and direction of the external electric field.
Effect of an intense laser field on the holes in graded quantum wells
(SPRINGER HEIDELBERG, 2013) Ozturk, Emine
The potential profile and the energy levels of the heavy holes (hh) and light holes (lh) in graded quantum wells under an intense laser field are theoretically calculated within the framework of the effective mass approximation. The results obtained show that the energy levels can significantly be modified and controlled by intense laser field and potential height. The effect of the laser field and potential height on the energy difference changes the degree of confinement and the energy level numbers. Also, we have seen a replacement between the lh2 and hh4 sub-bands whenever the laser field reaches almost alpha(0) = 20 A for our parameters. We hope that the controlled effects of the confining potential resulting from the applied laser field will provide important improvement in new semiconductor device applications.
Effect of the intense laser field on the valance band for Ga1-xAlxAs/GaAs heterostructure
(ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD, 2009) Ozturk, Emine; Sokmen, Ismail
The energy levels of holes in symmetric single quantum well under the laser field are theoretically calculated within the framework of the effective mass approximation. Results obtained show that the potential profile and energy levels can significantly be modified and controlled by intense laser field and the well width. The effect of the laser field and the well width on the energy difference changes the degree of the confinement, and thus this behavior can be used to study these systems in regions of interest, without the need for the growth of many different samples. (C) 2008 Elsevier Ltd. All rights reserved.
The effects of hydrostatic pressure on the nonlinear intersubband transitions and refractive index changes of different QW shapes
(ELSEVIER SCIENCE BV, 2012) Ozturk, Emine; Sokmen, Ismail
In this study, the effects of hydrostatic pressure on the linear and nonlinear intersubband transitions and the refractive index changes in the conduction band of different quantum well shapes are theoretically calculated within framework of the effective mass approximation. Results obtained show that intersubband properties and the energy levels in different QWs can be modified and controlled by the hydrostatic pressure. The modulation of the absorption coefficients and the refractive index changes which can be suitable for good performance optical modulators and various infrared optical device applications can be easily obtained by tuning the hydrostatic pressure strength. (C) 2012 Elsevier B.V. All rights reserved.
Electric and intense laser field effect on the electronic properties of Ga1-xAlxAs/GaAs and Ga(1-x)ln(x)As/GaAs semi-parabolic quantum wells
(IOP PUBLISHING LTD, 2016) Ozturk, Emine
In the present study, the electronic properties of Ga1-xAlxAs/GaAs and Ga(1-x)ln(x)As/GaAs semi-parabolic quantum wells (SPQWs) are theoretically investigated as dependent on the intense laser field (ILF) and the electric field within the effective mass. All results show that the shape of the confined potential profile, the energy differences and the dipole moment matrix elements are varied as dependent on ILF and the applied electric field. The energy levels of different SPQWs give different results by varying ILF amplitudes and electric field. In the case of SPQW under ILF and the electric field, there are important modifications of the electrical states of SPQWs, due to the effects of confining the potential resulting from the applied electric field and ILF. The numerical results show that these applied fields have a significant effect on the electronic characteristics of SPQW structures. It is seen that the finding probabilities of the electrons in Ga1-xAlxAs/GaAs SPQW are more than Ga1-xInxAs/GaAs SPQW. Highlights The shape of SPQWs changes as dependent on ILF. The potential profile of SPQWs depends on the size and direction of the applied electric field. The energy level and the dipole matrix element vary with the changes in SPQW. The probability density for F = -30 kV cm(-1) are greater both F = 0 and F = 30 kV cm(-1) for both SPQWs. The finding probabilities of electrons in SPQWs under ILF are more than for zero ILF.
Intersubband transitions and refractive index changes in coupled double quantum well with different well shapes
(ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD, 2011) Ozturk, Emine; Sokmen, Ismail
In this study, both the linear intersubband transitions and the refractive index changes in coupled double quantum well (DQW) with different well shapes for different electric fields are theoretically calculated within framework of the effective mass approximation. Results obtained show that intersubband transitions and the energy levels in coupled DQW can importantly be modified and controlled by the electric field strength and direction. By considering the variation of the energy differences, it should point out that by varying electric field we can obtain a blue or red shift in the intersubband optical transitions. The modulation of the absorption coefficients and the refractive index changes which can be suitable for good performance optical modulators and various infrared optical device applications can be easy obtained by tuning applied electric field strength and direction. (C) 2011 Elsevier Ltd. All rights reserved.
Intersubband transitions in an asymmetric double quantum well
(ACADEMIC PRESS LTD ELSEVIER SCIENCE LTD, 2007) Ozturk, Emine; Sokmen, Ismail
The intersubband optical absorption in an asymmetric double quantum well for different barrier widths and the right well widths are theoretically calculated within the framework of effective mass approximation. The results obtained show that the intersubband transitions and the energy levels in an asymmetric double quantum well can be importantly modified and controlled by the barrier width and the well width. The sensitivity to the barrier and well widths of the absorption coefficient can be used in various optical semiconductor device applications. (c) 2006 Elsevier Ltd. All rights reserved.
Linear and nonlinear intersubband optical absorption coefficient and refractive index change in n-type delta-doped GaAs structure
(ELSEVIER SCIENCE BV, 2013) Ozturk, Emine; Ozdemir, Yasin
In the effective mass approximation, we have theoretically investigated the subband structure of single Si delta-doped GaAs by solving the Schrodinger and Poisson equations self-consistently. Both the linear and nonlinear intersubband optical absorption coefficients and the refractive index changes are calculated as dependent on the doping concentration and thickness. Our results show that the position and the magnitude of the linear and total absorption coefficients and refractive index changes depend on the doping concentration and thickness. The shape of potential profile and the subband energy differences are changed as dependent on the donor concentration and thickness. By considering the variation of the energy difference we can obtain a blue shift or a red shift in the intersubband optical transitions. The resonant peak of total absorption coefficient can be bleached at sufficiently high incident optical intensities. Such a dependence of the exciting optical intensity on the doping concentration and thickness can be very useful for several potential device applications. (C) 2013 Elsevier B.V. All rights reserved.
Linear and nonlinear optical absorption coefficients and refractive index changes in double parabolic-square quantum well as dependent on intense laser field
(SPRINGER HEIDELBERG, 2015) Ozturk, Emine
In this study, for double parabolic-square quantum well (DPSQW) the linear and nonlinear intersubband optical absorption coefficients and the refractive index changes are calculated as dependent on the intense laser field (ILF). Our results show that the location and the size of all absorption coefficients and refractive index changes depend on ILF. Also, we show that ILF provides an important effect on the electronic and optical properties of DPSQW, and the changes of the energy levels and the dipole moment matrix elements are dependent on the shape of the confinement potential. Such effects can provide methods to drive tunable semiconductor lasers, which may be tailored by quantum potential well parameters and by ILF values.
Linear and total intersubband transitions in the step-like GaAs/GaAlAs asymmetric quantum well as dependent on intense laser field
(SPRINGER HEIDELBERG, 2015) Ozturk, Emine
In this study, for a step-like GaAs-Ga1-xAlxAs asymmetric quantum well (AQW) the linear and total intersubband optical absorption coefficients and the refractive index changes are calculated as dependent on the intense laser field (ILF) and the right quantum well (RQW) width. Our results show that the location and the magnitude of all absorption coefficients and refractive index changes depend on ILF and the asymmetric parameter (d = L-R/L-L). Also, we showed that both ILF and d provide an important effect on the electronic and optical properties of step-like quantum well, and the changes of the energy levels, the dipole moment matrix elements and the resonant peak values of the absorption coefficients are dependent on the shape of the confinement potential. While for different asymmetric parameters the intersubband absorption spectrum shows blue shift up to the different critical ILF values, this spectrum shows red shift for ILF values greater than certain values. By considering the variation of the energy difference as dependent on the RQW width, for step-like QW the absorption spectrum shows blue or red shift. Especially, step-like QWs are used for producing terahertz radiation from intersubband transitions and they have more tunable structure parameters (the left (right) quantum well width, L-L(L-R), and the confinement potential in the left (right) hand side, V-L(V-R)) with respect to other asymmetric QWs (in the present study we used L-R = L-L/2, L-L, 3L(L)/2 and V-R = 2V(L)/3 values). This case provides a new degree of freedom for controlling the optical properties in quantum wells (QWs). In addition, the nonlinear optics underlying the application of the ILF to asymmetric potential heterostructures becomes a subject of present-day interest. In conclusion: i) The electronic and optical properties of the step-like AQW vary by increasing ILF. ii) ILF leads to major modifications on the shape of the confining potential. iii) The position and the size of all absorption coefficients and refractive index changes depend on ILF and the asymmetric parameter values. iv) The absorption spectrum shows blue or red shift by increasing ILF.
Nonlinear intersubband absorption and refractive index change in n-type delta-doped GaAs for different donor distributions
(SPRINGER HEIDELBERG, 2015) Ozturk, Emine
In this study, both the linear and nonlinear intersubband optical absorption coefficients and the refractive index changes are calculated for the uniform, triangular and Gaussian-like donor distribution. The Gaussian-like distribution differs from the Gaussian distribution other authors use. The electronic structure of n-type Si delta-doped GaAs has been theoretically calculated by solving the Schrodinger and Poisson equations self-consistently. Our results show that the location and the size of the linear and total absorption coefficients and refractive index changes depend on the donor distribution type. The shape of delta-effective potential profile and the subband properties are changed as dependent on the donor distribution model. Therefore, the variation of the absorption coefficients and refraction index changes, which can be appropriate for various optical modulators and infrared optical device applications can be smooth obtained by the alteration donor distribution model.
Nonlinear intersubband absorption and refractive index changes in square and graded quantum well modulated by temperature and Hydrostatic pressure
(ELSEVIER SCIENCE BV, 2013) Ozturk, Emine; Sokmen, Ismail
In this study, the effects of hydrostatic pressure and temperature on the linear and nonlinear intersubband transitions and the refractive index changes in the conduction band of square and graded quantum well (QW) are theoretically calculated within the framework of effective mass approximation. Results obtained show that the energy levels in different QWs and intersubband properties can be modified and controlled by the hydrostatic pressure and temperature. The modulation of the absorption coefficients and the refractive index changes which can be suitable for good performance optical modulators and various infrared optical device applications can be easily obtained by tuning the temperature and the hydrostatic pressure. (c) 2012 Elsevier B.V. All rights reserved.
Nonlinear intersubband transitions in a parabolic and an inverse parabolic quantum well under applied magnetic field
(ELSEVIER SCIENCE BV, 2014) Ozturk, Emine; Sokmen, Ismail
In this study, both the intersubband optical absorption coefficients and the refractive index changes as dependent on the magnetic field are calculated in a parabolic (PQW) and an inverse parabolic quantum well (IPQW) for different Al concentrations at the well center. Our results show that the position and the magnitude of the linear, nonlinear and total absorption coefficients and refractive index changes depend on the magnetic field strength and the Al concentration at the well center. By decreasing the Al concentration at the well center we can obtain a red shift and a blue shift in the intersubband optical transitions for PQWs and IPQWs, respectively. Thus, the absorption coefficients and the refractive index changes which can be suitable for great performance optical modulators and multiple infrared optical device applications can be easily obtained by tuning the applicable magnetic field value and the Al concentration at the well center. (C) 2013 Elsevier B.V. All rights reserved.
Nonlinear intersubband transitions in asymmetric double quantum wells as dependent on intense laser field
(SPRINGER, 2016) Ozturk, Emine
In this study, for asymmetric double quantum well (ADQW) the linear and nonlinear intersubband optical absorption coefficients and the refractive index changes are examined as dependent on the intense laser field (ILF). The obtained results display that the location and the size of all absorption coefficients and refractive index change depend on ILF and the asymmetric parameter. Also, I showed that ILF provides an important effect on the electronic and optical properties of ADQW, and the changes of the energy levels and the dipole moment matrix elements are dependent on the shape of the confinement potential. Such effects can supply methods to drive tunable semiconductor lasers, which may be tailored by quantum potential well parameters and ILF values.
Nonlinear intersubband transitions in different shaped quantum wells under intense laser field
(ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD, 2015) Ozturk, Emine
In this study, the intersubband optical absorption coefficients and the refractive index changes are calculated in a square quantum well (SQW), a parabolic quantum well (PQW), a graded quantum well (GQW) and a V-shaped quantum well (VQW), without and with the intense laser field (ILF). Our results show that the position and the magnitude of the linear, nonlinear and total absorption coefficients and refractive index changes depend on ILF parameter and the quantum well (QW) shape. While for SQW the intersubband absorption spectrum shows blue shift up to the critical ILF value, this spectrum shows red shift for greater ILF values than this certain value. Whereas, for PQW, GQW and VQW the absorption spectrum shows always red shift by increasing ILF. Thus, the intersubband absorption coefficients and the refractive index changes which can be suitable for great performance optical modulators and multiple infrared optical device applications can be easily obtained by tuning ILF value and QW shape. (C) 2015 Elsevier Ltd. All rights reserved.
Nonlinear Intersubband Transitions in Square and Graded Quantum Wells Modulated by Intense Laser Field
(IOP PUBLISHING LTD, 2014) Ozturk, Emine; Sokmen, Ismail
The intersubband optical absorption coefficients and the refractive index change depending on the intense laser field (ILF); both are calculated in a square quantum well (SQW) and a graded quantum well (GQW). Our results show that the position and the magnitude of the linear, nonlinear and total absorption coefficients and refractive index changes depend on the laser field parameter and the quantum well (QW) shape. By increasing the ILF value, we can obtain a red shift or a blue shift in the intersubband optical transitions as dependent on the shape of the QW. For the SQW, the intersubband absorption spectrum shows a blue shift up to the critical laser field value. This spectrum shows a red shift for ILF values larger than this certain value. For the GQW, the intersubband absorption spectrum shows a red shift by increasing the ILF. Thus the absorption coefficients and the refractive index changes, which can be suitable for great performance optical modulators and multiple infrared optical device applications, can be easily obtained by tuning the ILF value and the QW shape.
Resonant peaks of the linear optical absorption and rectification coefficients in GaAs/GaAlAs quantum well: Combined effects of intense laser, electric and magnetic fields
(WORLD SCIENTIFIC PUBL CO PTE LTD, 2015) Ozturk, Emine; Sokmen, Ismail
In this study, the resonant peaks of the linear optical absorption (OA) and rectification coefficients in GaAs/GaAlAs quantum well are calculated as dependent on the applied electric field (F), the magnetic field (B) and the laser field intensity parameter (alpha(0)). Our results show that the shape of confined potential profile, the energy levels and the dipole moment matrix elements are changed as dependent on the F, B and alpha(0). Also, the resonant peaks of the OA and rectification coefficients depend on the applied external field effects. Therefore, the variation of the resonant peaks of these coefficients which can be appropriate for various optical modulators and infrared optical device applications can be smoothly obtained by the alteration electric, magnetic and intense laser field.

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