Binding energies of excitons in symmetric and asymmetric quantum wells in a magnetic field

Theoretical Study of the Exciton Binding Energy and Exciton Absorption in Different Hyperbolic-Type Quantum Wells under Applied Electric, Magnetic, and Intense Laser Fields

“…Moreover, before the growth of any low-dimensional quantum structure, it will be very practical and instructive to create and study the single, double, or triple quantum wells by selecting the appropriate hyperbolic potential functions and their different combinations by using the relevant material parameters. Finally, we would like to emphasize that the results we obtained in this study are quite consistent with the results of similar studies on QWs [ 33 , 54 , 55 , 56 ]. In particular, we want to emphasize that the maximum binding energy values that we found in this investigation for the strong confinement regime (the situation in which the electron and hole wavefunctions overflow into the barrier regions) are in excellent agreement with the report of Belov and Khramtsov for excitons in narrow quantum wells [ 57 ].…”

“…For z -polarized incident radiation, and the allowed interband transitions between the first heavy-hole and the first electron subbands, the first factor on the right-hand side in Equation ( 11 ) satisfies the condition [ 52 , 53 ] where is the Kane matrix element. Thus, inputting Equation ( 12 ) into Equation ( 10 ), and considering the Lorentzian representation of the -Dirac function, for excitons in a two-dimensional QW, the absorption coefficient, for heavy-hole electron transition [ 40 , 54 ], reduces to where is the well width (it should be noted that effective length has the form of for double hyperbolic QW with potential), is the broadening parameter of the Lorentzian function, is the band gap corresponding to GaAs material, is photon energy required for the transition to conduction band from valence band, and is overlap integral between the electron and hole wavefunctions [ 55 ]. In this context, the term in the denominator of the last factor in Equation ( 13 ) is the interband transition energy (ITE), which we defined as .…”

Binding energy of excitons in symmetric and asymmetric coupled double quantum wells in a uniform magnetic field

“…This happens because at larger well widths the extension of the wavefunction in the x-y plane increases, and this increases the contribution of the magnetic term of the Hamiltonian which is proportional to γ 2 ρ2 (equation ( 4)). Thus the increment of this positive term, which is more significant at large magnetic fields, gives a decrease in the excitonic binding energy [39,40]. The effect of the coupling and symmetry on the exciton binding energy is depicted in figure 3 where exciton binding energy is plotted versus barrier width for several magnetic field values for the ADQW.…”

Shallow donor impurities in different shaped double quantum wells under the electric field

“…Among the various systems under current investigation, the quantum wells (QWs) have attained considerable theoretical experimental attention. The QWs are commonly taken to be symmetric, but the asymmetric QWs give new tunable properties, which are very important for device applications [1][2][3][4][5][6]. Within the last few years, there has been great interest in the electronic properties in the asymmetric quantum well (AQW) structures because they are the ideal systems for the study of terahertz electromagnetic radiation from semiconductor heterostructures [7 -14].…”