S.S. Chandvankar

Surface photovoltage spectroscopy of n-n+ and p-n+ AlGaAs/GaAs heterojunctions

A comparative study of n-n+ and p-n+ semiconductor heterojunctions has been done using the surface photovoltage spectroscopy (SPS) in the chopped light geometry. Heterojunctions n-Al0.4Ga0.6As/n+ GaAs and p-Al0.37Ga0.67As/n+ GaAs and substrate n+ doped GaAs have been studied in the wavelength range 600–1000 nm. A sharp decrease in SPS at the band-gap energies of AlGaAs and GaAs with a broad peak in the subband-gap region of GaAs has been observed. The magnitude of surface photovoltage (SPV), for a constant photon flux for n-n+ samples, is less by more than two orders of magnitude than that for p-n+ samples in the wavelength range 645–870 nm. Changes in the dipole moments due to the redistribution of excess carriers in the space-charge regions are in opposite directions of the n-n+ heterojunctions giving less SPV, while for p-n+ heterojunction, the changes in the dipole moments are in the same direction giving more SPV in comparison to the n-n+ samples.

LPE Growth of GaSb from Ga and Sn solutions

Abstract Smooth epitaxial growth of GaSb from Ga and Sn solutions at 500°C is obtained. The growth rate from Sn solutions is found to be considerably larger than from Ga solutions. A portion of the Ga-Sb-Sn liquidus has been determined in the range of 400 to 510°C.

LPE growth of Ge-doped InGaAsP/InP by two-phase solution technique

Abstract Germanium doping of In 1- x Ga x As y P 1- y ( E g ≈ 0.95 eV) layers grown by LPE using two-phase solution technique produces n-type layers with distribution coefficient k Ge ≈ 4.5 × 10 -3 . In addition, Ge doping gives rise to a new band of luminescence.

Ge doping of liquid phase epitaxial In0.53Ga0.47As

Abstract Germanium doping of In 0.53 Ga 0.47 As grown by liquid phase epitaxy compensates the nominally n-type layers. At higher doping levels, the layers become p-type with significant compensation.

Ge Related Defect-Complex Induced Luminescence in InGaAsP

Germanium doping of InGaAsP epitaxial layers grown by liquid phase epitaxy produces n type conduction with a net distribution coefficient K Ge ∼ 5×10 -3 . In addition, Ge doping introduces a broad band (∼0.2eV) of efficient luminescence which is red shifted with respect to the band edge. The intensity of this band grows with increasing Ge concentration. In all the samples, the integrated intensity of the broad band varies relatively less in the temperature range 15K to about 90K. At higher temperatures, the intensity falls exponentially with an activation energy of 0.05 - 0.07 eV. The emission spectra are compared with the configuration-coordinate model of the emission from a Ge related complex.

Investigation of the role of tail-states in broad-band photoluminescence of heavily doped In0.72Ga0.28As0.60P0.40:Ge

Abstract A broad (0.2eV) photoluminescence band is introduced by n-type Ge doping of In 0.72 Ga 0.28 As 0.60 P 0.40 . This band is analysed by a model calculation of radiative transitions with multiphonon emission from conduction-band to impurity-disorder induced tail states near the valence-band edge.