The Effects of Spacer Thickness and Temperature on the Transport Properties of Modulation-Doped In0.53Ga0.47As/In0.52Al0.48As Heterojunctions

Abstract

The measurements of resistivity and low-field Hall effect made in the temperature range 3.3-295 K have been used to investigate the transport properties of modulation-doped, lattice-matched In 0.53 Ga 0.47 As/In 0.52 Al 0.48 As heterojunctions as a function of the spacer thickness in the range from 0 to 400 A. It is found that the sheet carrier density determined at temperatures below about 80 K decreases rapidly with increasing spacer thickness. The low-temperature Hall mobility increases substantially when increasing the spacer thickness from 0 to 100 A, and decreases gradually with further increase in spacer thickness. The results suggest that, in addition to alloy scattering, remote ionized-impurity scattering is a major scattering mechanism at low temperatures in the samples with thin spacer layer and that background impurity scattering prevails in the samples with spacer thickness larger than about 100 A. The effect of modulation doping on the mobility decreases progressively with increasing temperature: the electron mobility becomes practically independent of spacer thickness in the temperature range above about 200 K. The variation of Hall mobility with temperature in the range above 90 K has been used to determine the energy of longitudinal optical phonons that limit the mobility of electrons at high temperatures.On the Transport Properties of Modulation-Doped In 0.53 Ga 0.47 As/In 0.52 Al 0.48 As

Determination of the In-Plane Effective Mass and Quantum Lifetime of 2D Electrons in Modulation-Doped In0.53Ga0.47As/In0.52Al0.48As Heterojunctions from the Quantum Oscillations in Hall Resistance

“…The carrier density of 2D electrons, the Fermi energy and subband separation determined independently from the Hall oscillations and the SdH effect measurements [12] are in very good agreement. The total 2D carrier density (N 1 + N 2 ) in the modulation-doped In 0.53 Ga 0.47 As/ In 0.52 Al 0.48 As heterojunctions determined from the Hall oscillations are compared in Table 1 with the sheet carrier density (N H ), as obtained from the low-field Hall effect measurements [12,16]. It can be seen from the table that (N 1 + N 2 ) ffi N H for the sample with double-subband occupancy.…”

“…Theoretical calculations relating the transport lifetime to the quantum lifetime predict a t t /t q ratio much greater than unity for small-angle scattering and equal to or smaller than unity for large-angle scattering in the extreme quantum limit for single-subband occupancy [29][30][31]. This implies that in our samples the scattering of electrons in the first subband with remote ionized impurities and alloy disorder, which are the dominant scattering mechanisms at low temperatures [12,16], is on average forward displaced in momentum space. The relatively smaller value found for the ratio t t2 /t q2 of the second subband suggests that there is some contribution due to large-angle scattering.…”

Temperature dependent energy relaxation time in AlGaN/AlN/GaN heterostructures

“…1). This behavior reflects the 2D character of the electrons in the channel [19][20][21]. It is also evident that the oscillatory effect is superimposed on a monotonically increasing component, which occurs as a result of positive magnetoresistance in the barriers [7,19].…”