Photoluminescence and electrical properties of MOVPE-grown zinc-doped gallium antimonide on gallium arsenide

The growth of Zn-doped GaSb on GaAs substrate by metalorganic vapor phase epitaxy (MOVPE) at atmospheric pressure was studied using photoluminescence (PL) and van der Pauw-Hall techniques. The reactants used were trimethylgallium TMGa and trimethylantimony TMSb. Diethylzinc DEZn was used as the dopant source. The mole fraction of DEZn in the growth gas [DEZn] was varied between 3 × 10−7and 2.7 × 10−5corresponding hole concentrations between 1.4 × 1017cm−3and 1.7 × 1019cm−3, respectively. The relationship between the free hole concentration pand the [DEZn] is pα [DEZn]1.2. PL as a function of the temperature and excitation power was measured. The low-temperature PL exhibits one dominating band to zinc acceptor transition located at the energy of 798 meV in the least doped sample with [DEZn] = 3 × 10−7. The zinc acceptor energy level of about 13 meV above the valence band is determined from the PL peak maximum energy and the temperature dependence of the PL spectra. The maximum of the band to acceptor transition moves to lower photon energies with increasing zinc doping. The band-gap shrinkage as a function of the hole concentration is discussed.