Device quality n-type layers produced by ion implantation of Te and S into GaAs

The production of high quality n-type ion implanted layers suitable for GaAs MESFET device fabrication has been accomplished. The layers produced by implantation into low doped LPE layers are superior to those produced by implantation into semi-insulating substrates. The doping efficiency of the implanted and annealed layers increases with sample temperature during the implants reaching 85% for moderate dose implants of S at 500°C for layers annealed at 900°C. Annealing the implanted layers at 900°C for 15 minutes with a CVD Si
3
N
4
protective layer produces n-type layers with Hall mobilities of 4500 cm
²
V
^-1
s
^-1
for Te and 5000 cm
²
V
^-1
s
^-1
for S implants at peak concentrations of 10
¹⁷
cm
^-3
.