TEMPERATURE-DEPENDENT ELECTRICAL-PROPERTIES OF HEAVILY CARBON-DOPED GAAS GROWN BY LOW-PRESSURE METALORGANIC CHEMICAL-VAPOR-DEPOSITION

Abstract

The temperature dependence of the electrical properties of heavily carbon (C)-doped GaAs has been analyzed by Van der Pauw-Hall measurements. All samples were grown by low-pressure metalorganic chemical vapor deposition (MOCVD). At low temperature range (T < 100 K) the mobility curves were almost flat, however, at high temperature range (T > 100 K) the mobility values were decreased due to lattice phonon scattering. With decreasing the temperature, the carrier concentration was nearly the same, and even at low temperature range the carrier concentration was not frozen out. The resistivity increased at high temperature due to decreased mobility, but it did not increase in the low temperature range. All these electrical properties proved the degenerate conduction of heavily C-doped GaAs. The temperature dependence of mobility was analyzed using a simple analytical equation in the strongly degenerate limit and with constant effective mass. There was no compensation in the C-doped GaAs epilayer with p = 4.25 x 10(19) cm(-3), however there was some compensation (theta = N-d/N-a = 0.02) in the epilayer with p = 1.01 x 10(20) cm(-3). Thus it is suggested that heavily C-doped GaAs grown by low-pressure MOCVD exhibits a little or no compensation in the epilayers, and our simple analysis can explain the temperature dependence of Hall mobility of heavily C-doped GaAs epilayer very well.