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 cm
²
. V
^-1
. S
^-1
with over 85-percent activation for a Si dose of
5 \times 10^{12}
cm
^-2
. Dopant depth profiles with peak donor densities of
2 \times 10^{17}
cm
^-3
and 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 exhibited
g_{m} \geq 160
mS/mm and pinchoff voltages in the range of 3 V.