Boron-doped homoepitaxial diamond layers: Fabrication, characterization, and electronic applications

For electronic applications. a series of boron-doped homoepitaxial diamond layers of high crystal quality have been grown on (100)-cut diamond substrates using the microwave plasma CVD method. The B-concentration varies from 3x10(17) to 3x10(20) atoms/cm(3). The layers are selectively grown into the shape of Hall bars using a sputtered SiO2 mask. The diamond substrates are 3x3x1 mm(3) in size. Gold wires are bonded to ohmic contacts on the Hall bars formed by an electron beam evaporated Mo/Pt/Au sandwich annealed at 950 degrees C for 30 min. Electrical characterization is performed in eight samples over the temperature range from 100 to 1300 K. The results are discussed in detail. For diamond layers grown on synthetic nitrogen-doped (type Ib) substrate, current-voltage characteristics of diode type can be observed in the temperature range from 360 to 900 degrees C. Green electroluminescent light is emitted from the p-n junction area. High current Schottky diodes are also fabricated which consist of a gold contact to a moderately B-doped homoepitaxial layer grown on a synthetic heavily boron-doped (type IIb) substrate.