P. Modak

Si incorporation and Burstein-Moss shift in n-type GaAs

Silane (SiH4) was used as an n-type dopant in GaAs grown by low pressure metalorganic vapor phase epitaxy using trimethylgallium (TMGa) and arsine (AsH3) 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 SiH4 mole fraction, growth temperature, TMGa and AsH3 mole fractions on the Si incorporation efficiency have been studied. The electron concentration increases with increasing SIH4 mole fraction, growth temperature, and decreases with increasing TMGa and AsH3 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) - 1.5 x 10(18) cm(-3)). 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, Delta E(n) (eV) = 1.4 x 10(-8) n(1/3). We also obtained an empirical relation for the band gap shrinkage, Delta E-g in Si-doped GaAs as a function of electron concentration. The value of Delta E-g (eV) = -2.75 x 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 AsH3 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

Zn incorporation and band gap shrinkage in p-type GaAs

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 empiric...

PHOTOLUMINESCENCE STUDIES ON SI-DOPED GAAS/GE

Photoluminescence (PL) spectroscopy has been used to study the silicon incorporation in polar GaAs on nonpolar Ge substrates. Shifts of PL spectra towards higher energy with growth temperature, trimethylgallium (TMGa) and arsine

OMVPE growth of undoped and Si-doped GaAs epitaxial layers on Ge

(AsH_3)

Low temperature photoluminescence properties of Zn-doped GaAs

mole fractions were observed. The full width at half maximum increases with increasing growth temperature,

Comparative studies of Si-doped n-type MOVPE GaAs on Ge and GaAs substrates

AsH_3

Effect of V/III ratio on the optical properties of MOCVD grown undoped GaAs layers

and TMGa mole fractions. The peak at 1.49 eV has been attributed to band-to-acceptor transition involving residual carbon. The PL peak energy shifts towards higher energy with increasing growth temperature due to the increase in electron concentration. A vacancy control model may explain the PL shift towards higher energy with increasing AsH3 mole fraction. The PL peak shifts towards higher energy with increasing TMGa mole fraction. The experimental results about the growth temperature, trimethylgallium, and arsine mole fractions on silicon- doped GaAs on GaAs were presented for comparison. The outdiffusion of Ge into the GaAs epitaxial layer was hardly to be seen from the secondary ion mass spectroscopy result.

Growth and Characterization of GaAs Epitaxial Layers by MOCVD

Low-pressure organometallic vapor-phase epitaxial (LP-OMVPE) growth of undoped and Si-doped GaAs on Ge was carried out with a variation in growth temperature and growth rate. In the case of undoped and Si-doped GaAs, etch patterns showed that the epilayers consist of a single domain. Double crystal X-ray diffraction (DCXRD) indicated the compressive GaAs and the full-width at half-maxima for Si-doped GaAs decreased with increasing growth temperature. The 4.2 K photoluminescence (PL) spectrum of the undoped GaAs showed an acceptor bound excitonic peak (A0X transition) at 1.5125 eV and the Si-doped GaAs showed two hole transitions of Si acceptors at 1.4864 eV along with the excitonic peak at 1.507 eV. This indicated the absence of Ge related peaks, i.e., (e-GeAs0) transitions. The electrochemical capacitance voltage profiler showed that the Si-doping efficiency for GaAs on Ge was less than that in GaAs on GaAs. The profiler revealed an npn structure in both the cases where the p region was in GaAs. The secondary ion mass spectroscopy (SIMS) results qualitatively indicated the absence of outdiffusion of Ge into GaAs.

Structural and electrical properties of undoped GaAs grown by MOCVD

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

Effect of V/III ratio on the optical properties of LPMOVPE grown undoped GaAs epi-films

(10^{17}-1.5x10^{20} cm^{-3})