The current-voltage characteristics of Au/lowdoped n-GaAs Schottky diodes were determined at various temperatures in the range of 77-300 K. The estimated zero-bias barrier height and the ideality factor assuming thermionic emission (TE) show a temperature dependence of these parameters. While the ideality factor was found to show the T 0 effect, the zero-bias barrier height was found to exhibit two different trends in the temperature ranges of 77-160 K and 160-300 K. The variation in the flat-band barrier height with temperature was found to be −(4.7 ± 0.2) × 10 4 eVK −1 , approximately equal to that of the energy band gap. The value of the Richardson constant, A * * , was found to be 0.27 A cm −2 K −2 after considering the temperature dependence of the barrier height. The estimated value of this constant suggested the possibility of an interfacial oxide between the metal and the semiconductor. Investigations suggested the possibility of a thermionic field-emission-dominated current transport with a higher characteristic energy than that predicted by the theory. The observed variation in the zero-bias barrier height and the ideality factor could be explained in terms of barrier height inhomogenities in the Schottky diode.

Dimethylzinc (DMZn) was used as a p-type dopant in GaAs grown by low pressure metalorganic vapor phase epitaxy using trimethylgallium and arsine (AsH3) as source materials. The hole carrier concentrations and zinc (Zn) incorporation efficiency are studied by using the Hall effect, electrochemical capacitance voltage profiler and photoluminescence (PL) spectroscopy. The influence of growth parameters such as DMZn mole fraction, growth temperature, and AsH3 mole fraction on the Zn incorporation have been studied. The hole concentration increases with increasing DMZn and AsH3 mole fraction and decreases with increasing growth temperature. This can be explained by vacancy control model. The PL experiments were carried out as a function of hole concentration (1017–1.5×1020 cm−3). The main peak shifted to lower energy and the full width at half maximum (FWHM) increases with increasing hole concentrations. We have obtained an empirical relation for FWHM of PL, ΔE(p)(eV)=1.15×10−8p1/3. We also obtained an empirical relation for the band gap shrinkage, ΔEg in Zn doped GaAs as a function of hole concentration. The value of ΔEg(eV)=−2.75×10−8p1/3, indicates a significant band gap shrinkage at high doping levels. These relations are considered to provide a useful tool to determine the hole concentration in Zn doped GaAs by low temperature PL measurement. The hole concentration increases with increasing AsH3 mole fraction and the main peak is shifted to a lower energy side. This can be explained also by the vacancy control model. As the hole concentration is increased above 3.8×1018 cm−3, a shoulder peak separated from the main peak was observed in the PL spectra and disappears at higher concentrations.

Silane (SiH 4 ) was used as an n-type dopant in GaAs grown by low pressure metalorganic vapor phase epitaxy using trimethylgallium (TMGa) and arsine (AsH 3 ) as source materials. The electron carrier concentrations and silicon (Si) incorporation efficiency are studied by using Hall effect, electrochemical capacitance voltage profiler and low temperature photoluminescence (LTPL) spectroscopy. The influence of growth parameters, such as SiH 4 mole fraction, growth temperature, TMGa and AsH 3 mole fractions on the Si incorporation efficiency have been studied. The electron concentration increases with increasing SiH 4 mole fraction, growth temperature, and decreases with increasing TMGa and AsH 3 mole fractions. The decrease in electron concentration with increasing TMGa can be explained by vacancy control model. The PL experiments were carried out as a function of electron concentration (10 17 −1.). The PL main peak shifts to higher energy and the full width at half maximum (FWHM) increases with increasing electron concentrations. We have obtained an empirical relation for FWHM of PL,. We also obtained an empirical relation for the band gap shrinkage, DE g in Si-doped GaAs as a function of electron concentration. The value of DE g (eV) = −2.75×10 − 8 n 1/3 , indicates a significant band gap shrinkage at high doping levels. These relations are considered to provide a useful tool to determine the electron concentration in Si-doped GaAs by low temperature PL measurement. The electron concentration decreases with increasing TMGa and AsH 3 mole fractions and the main peak shifts to the lower energy side. The peak shifts towards the lower energy side with increasing TMGa variation can also be explained by vacancy control model.

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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 (10 17 −1.5×10 20 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, DEp, band gap, Eg, and band gap shrinkage, DEg 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.