Molecular beam epitaxial growth of GaAs millimeter-wave IMPATT diode material

Abstract

GaAs millimeter-wave IMPATT diode material has been grown by molecular beam epitaxy. The epitaxial structure contained the double-drift Read doping profile. Silicon and beryllium were used as the N- and P-type dopants, respectively. The N and P spikes were 300 Å wide and separated by 800 Å of doped material. The substrate temperature was 590 °C and the growth rate was 1 μm/h. Although some Debye spreading is present in this thin-layered structure, useful doping versus depth information was obtained by capacitance–voltage (C–V) profiling. From the C–V measurements and secondary ion mass spectrometry measurements we did not observe any significant diffusion of the silicon and beryllium dopants with the above growth conditions. The maximum doping level of the spikes was 1×1018 cm−3. The epitaxial material was fabricated into single-mesa IMPATT diodes. Sharp reverse breakdown characteristics were obtained. The uniformity of the breakdown voltages over a 1 in. radius of the wafer was excellent. Initial rf measurements have been performed at 60 GHz. A cw power of 1.24 W with 11.4% efficiency was measured at 60.5 GHz. The diodes exhibit good ruggedness. Junction temperatures in excess of 250 °C have been obtained without burnout.