Chemical epitaxy of CdSe on GaAs†
We have studied chemical bath-deposited CdSe thin films on GaAs substrates. The films deposited on GaAs(100) showed a (001) textured polycrystalline zinc blende CdSe layer at the interface. On top of this layer, a stable form of wurtzite CdSe was obtained, where the CdSe grew in highly defective columnar crystals. The defects were mostly stacking faults, which have been well documented in the literature for CdSe due to polytypism. Deposition on GaAs(111)A and GaAs(111)B resulted in monocrystalline films of wurtzite CdSe with their c-axis oriented perpendicularly to the substrate surface. The effects of the pH value, growth time and temperature deposition parameters were investigated. At an optimal pH value of 12.3, a linear growth rate was observed as a function of growth time. Arrhenius plots provided the activation energies associated with chemical bath deposition of CdSe on GaAs. The lowest activation energy for CdSe film formation was obtained on GaAs(111)B as compared to growth on GaAs(100) and GaAs(111)A substrates.