Low temperature photoluminescence properties of Zn-doped GaAs

Abstract

Dimethylzinc (DMZn) was used as a p-type dopant in GaAs grown by low pressure metalorganic chemical vapor deposition (MOCVD). The influence of growth parameters, such as, DMZn mole fractions, growth temperature, trimethylgallium (TMGa) mole fractions, substrate surfaces on the Zn incorporation have been studied. The surface morphology of the layers was measured by scanning electron microscopy (SEM). The hole concentrations and zinc (Zn) incorporation efficiency are studied by using Hall effect, electrochemical capacitance voltage (ECV) profiler, and low temperature photoluminescence (LTPL) spectroscopy as functions of hole concentration (10¹⁷-1.5×10²⁰ cm^-3) and experimental temperatures (4.2-300 K). The hole concentration increases with increasing DMZn and TMGa mole fractions and decreases linearly with increasing growth temperature. The main PL peak shifted to lower energy and the full width at half maximum (FWHM) increased with increasing hole concentration. An empirical relation for FWHM, ΔEp, band gap, Eg, and band gap shrinkage, ΔEg in Zn doped GaAs as a function of hole concentration were obtained. These relations are considered a useful tool to determine the hole concentration in Zn doped GaAs by low temperature PL measurement. The hole concentration increases with increasing TMGa mole fraction and the main peak is shifted to lower energy side.