The Effect of Uniaxial Stress on the Density of States of Shallow Donor Impurities in GaAs Quantum Wells

Abstract

Seventeen standard platinum resistance thermometers from five commercial sources have been subjected to repeated thermal cycling over all or most of the range -196 "C to +650 "C to determine whether strain effects occur in the platinum sensors, and to what precision they affect temperature measurements. It is found that the resistance at the triple point of water, when measured repeatedly during thermal cycling, does undergo reversible changes in many thermometers that can be attributed to either elastic or anelastic strain. The magnitude of this resistance irreproducibility is usually between the equivalent of 0.1 m "C and 1.8 m "C near 0 "C. It is concluded that thermal strain effects pose a small, but significant, limitation on the ultimate performance of most of these thermometers.

A theoretical study of the effects of uniaxial stress and spatial dielectric functions on the density of states of shallow donor impurities in a GaAs quantum well dot of circular geometry

“…Furthermore, it is quite noticeable that DOIS is higher when Hermanson's and linearized Thomas-Fermi spatial dielectric functions are applied than when a dielectric constant is used right from the onset of DOIS through their peaks. It has been observed in other works [29,30] that the dielectric function enhances donor binding energy. This means that the donor impurity becomes more tightly bound to its parent ion and, therefore, presents a larger DOIS profile than when the dielectric constant is used.…”

“…The results for the DOIS for all the cases clearly show an important feature that is a peak at lower binding energies, which is the signature for QD structures. This is as a result of the contribution of impurities near the axial edge of the quantum well dot [29]. This effect becomes more pronounced as the dimensionality of the active layer is reduced making injected charge carriers to concentrate in an increasingly narrower energy range near the band edge.…”

A theoretical study of variation of photoionization cross section of donor impurities in a GaAs quantum dot of cylindrical geometry with incident photon frequency, donor location along the dot axis and applied uniaxial stress

“…Of these, one semiconductor material that has been of great interest for device application is Gallium Arsenide (GaAs). The GaAs has been studied extensively both experimentally and theoretically [6][7][8][9][10][11][12][13][14]. These studies have been directed towards determining its potential for optical and electronic device applications.…”

“…Studies have been carried out on donor impurity binding energies in GaAs quantum wells [14,15], quantum well wires [16] and quantum dots [17][18][19]. Further work has seen the use of the binding energies to compute density of impurity states [9] and photoionization cross-sections [20][21][22][23][24][25][26] when the system is subjected to external constraints. In our previous work [26], we have studied the effect of Hermanson's spatial dielectric function, finite and infinite barrier potentials and axial lengths on the photoionization cross-section of a hydrogenic and a non-hydrogenic donor impurity in a GaAs quantum well dot (QWD) of circular cross-section.…”