Preparation of GaAs microwave devices by molecular beam epitaxy

The molecular beam epitaxy technique has been used to prepare IMPATT and mixer diodes with GaAs. Precise doping profile control is achieved by the use of carefully controlled beams of Sn, Si or Ge and an understanding of the doping profiles resulting from a given beam intensity-time profile. Planar isolation is achieved because it is possible to grow semi-insulating poly-crystalline material on an amorphous coating on a substrate while simultaneously growing high quality doped single crystalline material on the substrate exposed through windows in the amorphous coating. Large area (2 cm × 2 cm) layers and layers consisting of semi-insulating areas containing isolated devices have been grown.