Growth of thick liquid-phase epitaxial GaAs : Si layers and their characterization

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Abstract
In this study we compare some of the characteristic properties of liquid‐phase epitaxial (LPE) layers of heavily Si‐doped GaAs with those of melt‐grown GaAs : Si. LPE layers are grown isothermally at 750, 840, and 910 °C. All the layers are p type and have room‐temperature carrier concentrations between 4.2×1017 and 4.8×1018 cm−3. Low‐temperature photoluminescence measurements of the layers show a single broad band peaked near 1.32 eV, the peak shifting slightly to lower energy after annealing at 1100 °C. Infrared absorption measurements at ∼80 °K of electron‐irradiated layers showed SiGa, SiAs, and SiGa‐SiAs localized vibrational modes. The integrated absorptions indicate that the Si site distribution is not compatible with p‐type conduction and a new acceptor defect is required. Transmission electron microscopy indicates that the layers have very few vacancy‐type prismatic dislocation loops and are essentially free of stacking faults. It is concluded that the LPE layers are basically different than melt‐grown GaAs : Si in that different acceptor species, other than SiAs, are present in the two materials and the characteristics of these different acceptors are discussed.