Selective epitaxial growth of GaAs by current controlled liquid phase epitaxy

摘要

Selective epitaxial growth of Te-doped GaAs on circularly patterned GaAs (100) substrate was investigated by liquid phase epitaxy (LPE) and current controlled liquid phase epitaxy (CCLPE). SiN_x was used as a mask layer to fabricate circular windows on the substrate and the effect of various growth periods and current densities on the growth morphology were investigated. A truncated pyramid like structure with a vertical thickness of 337 μm and a lateral thickness of 268 urn was achieved on the circularly patterned substrate at 6 h growth with an applied current density of 20 A cm~(-2). The vertical growth was increased almost one order and lateral growth was increased up to nine times compared to standard LPE growth. The growth step density was higher at window walls and it caused relatively higher growth compared to its centre. The surface morphology and selective epitaxial growth were greatly improved by an applied DC electric current. The dislocation density of the grown epilayer was significantly reduced when compared with that of the substrate. Solute transport in the solution was enhanced by the electromigration of solute by an electric current, which enhanced growth in vertical and lateral directions.