Temperature and electric field dependences of the mobility of electrons in vertical transport in GaAs/Ga1−y AlyAs barrier structures containing quantum wells

Abstract

The mobility of electrons in vertical transport in GaAs/Ga1−y AlyAs barrier structures was investigated using geometric magnetoresistance measurements in the dark. The samples studied had Ga1−y AlyAs (0 ≤ y ≤ 0:26) linearly graded barriers between the n+-GaAs contacts and the Ga0:74Al0:26As central barrier, which contain N w (=0, 2, 4, 7 and 10) n-doped GaAs quantum wells. The mobility was determined as functions of (i) temperature (80–290 K) at low applied voltage (0.01–0.1 V) and (ii) applied voltage (0.005–1.6 V) at selected temperatures in the range 3.5–290 K. The experimental results for the temperature dependence of low-field mobility suggest that space-charge scattering is dominant in the samples with N w=0 and 2, whereas ionized impurity scattering is dominant in the samples with N w=4, 7 and 10. The effect of polar optical phonon scattering on the mobility becomes significant in all barrier structures at temperatures above about 200 K. The difference between the measured mobility and the calculated total mobility in the samples with N w=4, 7 and 10, observed above 200 K, is attributed to the reflection of electrons from well-barrier interfaces in the quantum wells and interface roughness scattering. The rapid decrease of mobility with applied voltage at high voltages is explained by intervalley scattering of hot electrons.

Tunable p- and n-Type Tellurium-Free Mg3Bi2 Thermoelectric Thin Films by Thermal Coevaporation

“…This is particularly the case in the temperature range of 80–110 °C (Figure ). This can be attributed to competing impurity and lattice phonon scattering processes, dominant at lower and higher temperatures, respectively. , We should also remark that the measurements of the TE properties were conducted on Mg 3 Bi 2 samples annealed at 200 °C, which is below the crystallization temperature (300 °C; Figure b) of Mg-rich Mg 3 Bi 2 . Hence, the difference in the TE performance could also be related to the difference in crystallinity between the Mg-poor and Mg-rich samples.…”

Determinação da corrente de escuro em fotodetectores de radiação infravermelha baseados em poços quânticos (QWIPs)

“…A baixas temperaturas (T < 100K), o espalhamento por impurezas ionizadas [27,26] é dominante, e a mobilidade parcial relacionada é dada pelas expressões (Brook-Herring/Falicov):…”

“…A mobilidade relacionada com o espalhamento por fônons ópticos polares, o mais importante processo a temperaturas mais altas (T > 100K), é dada pelas expressões [26]:…”

“…As outras contribuições para a mobilidade total, menos importantes, são relacionadas com o espalhamento pela inomogeneidade da liga, µ a , o espalhamento pela distribuição de cargas ao longo de inomogeneidades do material (space charge), µ sc , e os espalhamentos pelos fônons acústicos: deformação de potencial, µ dp , e piezoelétrica, µ pe , e são dadas pelas equações [24,25,26]:…”