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a b s t r a c tSelective epitaxial growth of a GaAs layer on SiN x masked Si-doped semi-insulating (1 0 0) GaAs substrate was performed by current-controlled liquid-phase epitaxy (CCLPE) in the conventional liquidphase epitaxy. Experiments were carried out with and without the application of electric current. Surface morphology of (1 0 0) facet of the grown layer and the vertical and lateral growth rates were significantly improved under applied electric current. A thick layer of about 330 mm was achieved at relatively low growth time of 6 h with a current density of 20 Acm À2 . The epitaxial growth is realized by both electromigration of the solute and supercooling under a constant rate of furnace cooling. The dislocation density of the grown layer was significantly reduced, compared with that of the substrate (4 Â 10 4 cm 2 ).

a b s t r a c tThe 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 À 2], [0 1 À 1] and their equivalent seed orientations by current-controlled liquid phase epitaxy (CCLPE). SiO 2 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 mm in the [0 1 À 1] orientation and the largest lateral growth of 318 mm in the [0 1 2] orientation were achieved at 7.5 A cm À 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 À 2] seed orientations were suitable for application in a GaAs X-ray detector.