A simplified capless annealing of GaAs for MESFET applications

A simple capless annealing technique for post-implantation annealing of a GaAs wafer is described. The technique incorporates a novel boat design and uses InAs as the source of arsenic overpressure. Using this technique, wafers annealed at 850°C show mobilities in the range of 4000 cm². V^-1. S^-1with over 85-percent activation for a Si dose of5 times 10^{12}cm^-2. Dopant depth profiles with peak donor densities of2 times 10^{17}cm^-3and minimal tailing were demonstrated. Electron channeling data show that crystallinity is fully restored during the anneal. 1-µm gate length MESFET's processed on n⁺-n implanted layers exhibitedg_{m} geq 160mS/mm and pinchoff voltages in the range of 3 V.