K. Mallik et S. Dhar, DOMINANT TRAPS IN LIQUID-PHASE EPITAXIAL GAAS STUDIED BY CONTROLLED DOPING WITH INDIUM AND ANTIMONY, Physica status solidi. b, Basic research, 184(2), 1994, pp. 393-402
Photocapacitance measurements in the photon energy range of 0.64 to 1.
27 eV are done on GaAs layers grown by liquid phase epitaxy (LPE) and
doped with varying amounts of indium (In) and antimony (Sb). Two hole
traps with optical ionization energies of 0.65 and 0.79 eV are reveale
d in the material which are assumed to be two levels associated with t
he hole trap in reported in the literature. In addition, the hole trap
A, usually found in LPE GaAs is also detected here by optical deep le
vel transient spectroscopy (ODLTS) technique. The results of trap dens
ity measurements, as functions of isoelectronic doping concentration,
indicate that V(Ga) is an active constituent of the hole traps in LPE
GaAs. The concentration of the 0.79 eV trap is found to be reduced in
the material with high concentration of Sb. The analysis of photocapit
ance data using the existing theoretical models indicates the presence
of an electron trap with activation energy of 0.75 eV in the heavily
Sb-doped material. This trap may be identified with the second charge
state of the Sb(Ga) electron trap, obtained previously in bulk and met
alorganic vapor phase epitaxial GaAs doped with Sb. The sharp reductio
n of the 0.79 eV hole trap density in Sb-doped materials is explained
by assuming the complex Ga(As)V(Ga)- as its source.