Influence of the additional p⁺ doped layers on the properties of AlGaAs/InGaAs/AlGaAs heterostructures for high power SHF transistors

The 2DEG mobility enhancement for low- and high-electric fields in a new type of AlGaAs/InGaAs heterostructures with donor-acceptor doping

“…As one can see from Table 1, the 2DEG mobility for the DA-pHEMT heterostructures approximately is halved in comparison with the standard pHEMT heterostructures. This results from a higher density of the ionized donors in both -layers which leads to an increase in scattering on the ionized donors [4]. But the 2DEG mobility in DA-pHEMT heterostructures after splitting of the -layers becomes comparable with mobility in standard pHEMT heterostrutures.…”

“…Splitting of the -layers has been proposed to reduce the Coulomb scattering on the ionized donors that dominates at low temperatures in DA-pHEMT heterostructures [4]. So far such splitting has been applied only for suppression of parasitic parallel conductivity [6,7].…”

“…The values of the 2DEG density and mobility were determined from the variable-field Hall effect measurement by the Van der Pauw method at 77 K and 300 K temperatures in the magnetic field range of 0÷2 T by using the mobility spectrum analysis with multi-carrier fitting [4]. Ohmic contacts to the samples were fabricated by the high-voltage discharge through the indium foil imposed on the sample.…”

“…We assume that the 2DEG density does not have any dependence upon an electric field intensity. The EL radiation emitted from the samples under the voltage pulse was measured by the spectrometer on the basis of the single diffraction monochromator equipped with a Si CCD matrix at 300 K. The calculations of the 2DEG mobility limited by ionized-donors scattering were made at low temperature (77 K) according to the theoretical model described in our previous paper [4]. The broadening of the -layers was taken into account.…”

“…A new type of AlGaAs/InGaAs heterostructures with donor-acceptor doped barriers (DA-pHEMT) allows us to suppress the parasitic parallel conductivity via the δ-n-layers placed in the barriers and enhance the output power density of the DA-pHEMT transistor [3]. However, the electron mobility in DA-pHEMT heterostructures is lowered by scattering on ionized donors from the broadened δ-sublayers located in the barriers [4].…”