Orientation-dependent epitaxial growth of GaAs by current-controlled liquid phase epitaxy

The orientation dependence of the selective epitaxial growth of Gallium Arsenide (GaAs) has been investigated to achieve a thick epitaxial layer for application to X-ray detectors. Selective epitaxial growth was carried out on patterned GaAs with [0 1 1], [0 1 2], [0 1 0], [0 1 −2], [0 1 −1] and their equivalent seed orientations by current-controlled liquid phase epitaxy (CCLPE). SiO2 was used as a mask layer to fabricate the various seed orientations on the Si-doped GaAs (1 0 0) substrate and various growth periods and current densities were considered. Solute transport in the solution was enhanced by the electromigration of solute by an applied DC electric current, which caused an incremental growth in vertical and lateral directions in all orientations. The highest vertical thickness of 268 μm in the [0 1 −1] orientation and the largest lateral growth of 318 μm in the [0 1 2] orientation were achieved at 7.5 A cm−2 current density for 6 h. The seed aligned in the [0 1 2] orientation was favorable for high lateral growth of GaAs. The [0 1 1], [0 1 0] and [0 1 −2] seed orientations were suitable for application in a GaAs X-ray detector.