GAAS WITH VERY LOW ACCEPTOR IMPURITY BACKGROUND GROWN BY MOLECULAR-BEAM EPITAXY

We report very high purity, MBE grown, unintentionally doped, n-type GaAs with an extremely low acceptor background. The residual acceptor concentration is 2. 4 multiplied by 10**1**3 cm** minus **3 and the residual donor concentration is 1. 5 multiplied by 10**1**4 cm** minus **3, yielding a compensation ratio of N//a/N//d equals 0. 160. The measured Hall mobility is 163,000 cm**2/V multiplied by (times) s at 77 K with a peak value of 216,000 cm**2/V multiplied by (times) s at 45. 9 K. The photoluminescence spectrum shows that this material is only lightly compensated and exhibits the narrow linewidths that are characteristic of high GaAs. Hall measurements show excellent electrical uniformity across the wafer, even at low background doping.