Transport properties in GaAs-Al _x Ga _{1− x} As heterostructures and MESFET application

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

“…The initial enhancement of the mobility could be due to the reduction in remote ionized-impurity scattering with increasing spacer thickness. Since the high-temperature mobility is essentially controlled by optical phonon scattering and alloy scattering, which are expected to be insensitive to variations in the spacer thickness [21], the beneficial effect of modulation doping is progressively reduced at high temperatures: the electron mobility becomes practically independent of spacer thickness in the temperature range above about 200 K. This result is consistent with that in the case of modulation-doped GaAs/Ga x Al 1-x As heterojunctions where the room-temperature mobility of electrons was found [24,39] to be essentially independent of spacer thickness in the range from 0 to 300 A. By contrast, a marked increase in the room-temperature Hall mobility with increasing spacer thickness from 0 to 100 A was observed for d-doped In 0.53 Ga 0.47 As/In 0.52 Al 0.48 As MODFETs and attributed to the remote impurity scattering associated with the interface roughness caused by d-doping [13].…”

“…The results imply that the value of t S0 is independent of temperature in the range up to about 200 K, at higher temperatures the Hall mobility is practically independent of spacer thickness. Previous reports [39][40][41] on the variation of mobility with spacer thickness in modulation-doped GaAs/Ga 1Àx Al x As heterojunctions also showed the existence of an optimum spacer thickness (% 75 to 100 A), for thicker spacer layers the mobility was found to decrease. A favorable spacer thickness of about 100 to 200 A was also reported for modulation-doped Al x Ga 1-x N/GaN heterojunctions [37].…”

Electron mobility and landau level width in modulation-doped GaAs-AlxGa1−xAs heterojunctions

“…The results for sampies SI, S 2 and $3, which were grown in the same conditions, are plotted in Fig.4. These data exhibit a low temperature plateau of AB~ followed by a monotonic decrease in the phonon scattering regime, which is exactly the observed behaviour of the Hall mobilities [13]. Fig.4 also shows that AB~ increases monotonically with the thickness d of the spacer layer of undoped AlxGal_xAS, as expected from the increasing spatial separation of the electrons from their parent donors, and as already reported for the Hall mobility [14].…”

GaAs-AlGaAs Epitaxial Growth for Microwave Applications

“…Most of the works 2DEG have be done with the molecular beam epitaxy technique (MBE) (8,(13)(14)(15). More recently the metal-organic chemical vapor deposition (MOCVD) is following the way laid down by MBE (16)(17)(18).…”