Preparation of gallium nitride (GaN) and related compounds by plasma immersion ion implantation and rapid thermal annealing

Recent advances in the preparation of gallium nitride (GaN) and related compounds have promised the production of a blue semiconductor laser, a device that has long been desired for by the consumer electronics market. Conventional preparation involves growing GaN thin films on lattice-mismatching sapphire or silicon carbide using metal–organic chemical vapor deposition (MOCVD). In this article, we present an alternative method to produce a lattice-matching substrate for subsequent GaN growth, and to possibly synthesize device-grade GaN and related materials, like InN and InGaN, by plasma immersion ion implantation (PIII) followed by rapid thermal annealing. Our novel approach uses a broad ion-impact energy distribution and multiple implant voltages to form a spread-out nitrogen depth profile and an amorphous surface layer. This approach circumvents the retained-dose limitation and low nitrogen content problems associated with ion beam implantation at fixed energy. Based on our Raman study, the resulting structure after PIII and rapid thermal annealing is strained and contains some GaN, possibly in crystal form. The process still needs to be refined to make device-quality materials, but the present materials should suffice as a substrate on which lattice-matching GaN layers can be grown directly by MOCVD.