The individual subband densities and mobilities in delta -doped GaAs at different temperatures

Abstract

The transport properties of 6GaAs (Si) at high temperatures were studied using the 'mobility spectrum' technique. Strong changes in the subband occupancies were observed in a low-doped sample (No = 1.5 x 10'2cm-2) as the temperature increased from 77 K to 300 K while in a high-doped sample (ND = 5.0 x 1'0'~cm-~) these changes were small. For an explanation of the observed behaviour with temperature Poisson's and Schrddinger's equations were solved self-consistenti y. independent of temperature while the mobilities of the higher subbands (i > 0) decreased with increasing temperature in both IOW-and highdoped samples. At 'close to room temperature, the conductivity of the &structures can be described well by a two-carrier model where the first group of carriers consists of the electrons of t h e lowest subband and the second group consists of the electrons of all the higher subbands having approximately equal mobilities.The mobility of the lowest subband (i = 0) was found to be relatively

An investigation of the multicarrier transport properties of -doped InSb at high temperatures using a mobility spectrum technique

“…The high subbands appear as one peak in the MS as they have very similar mobilities and hence may be considered as one group of carriers. Earlier, a similar result for δ-GaAs was reported in [3] and [10]. As shown in figure 4, the density of high-mobility electrons (peak C) in sample #1369 is about 1.6 × 10 12 cm −2 up to 200 K, beyond which it increases rapidly with increasing temperature.…”

“…The independence of the concentration from the temperature can be explained by a large energy separation between the subbands which essentially exceeds the thermal energy in the relevant temperature interval up to room temperature. It was shown in [10] that in the case of δ-doped GaAs the subband energies and occupancies reveal an essential change at high temperatures when the difference between energy levels begins to be comparable to the thermal energy.…”

“…Methods based on the Shubnikov-de Haas (SdH) effect are not applicable at higher than liquid helium temperatures, as the SdH oscillations disappear at high temperatures. The most complete information about multi-subband conduction in δdoped structures at high temperatures can be obtained from the magnetotransport data using the mobility spectrum (MS) technique [9,10].…”

Classical magnetotransport in a parabolic quantum well with a strong intersubband scattering

“…In both systems several subbands can be occupied easily with a substantial portion of the electron population in the higher subbands. Much effort of researchers has been concentrated on transport properties of DDLs [8][9][10][11][12][13][14][15][16], and recently the PQWs have been receiving growing attention as well [17][18][19].…”

Electrical transport properties of silicon delta-doped Al0.30Ga0.70As samples showing suppression of the DX center features

“…We have also rejected the DX center as an alternative due to the small increment of the Hall density ͑only about 0.5ϫ10 12 cm Ϫ2 ) after intensive illumination at 4 K. However, one should be careful when comparing the Hall density and silicon concentration values, because the Hall density is a function of the concentrations and mobilities of all populated subbands. 17 Qualitatively, the behavior of the Hall density presents similar behavior for the three samples. The samples show a very low variation ͑less than one order of magnitude͒ undea high temperature range ͑150-300 K͒ and the curves do not fit a typical Arrhenius plot, which could be used to extract a thermal activation energy, eventually related to the DX center.…”