DEVICE PROPERTIES OF HOMOEPITAXIALLY GROWN DIAMOND

Homoepitaxial single-crystal diamond layers were grown on naturally occurring type Ia and IIa gemstone diamond substrates using microwave-plasma-assisted chemical vapor deposition techniques. The epitaxial layers ranged in thickness from 0.5 to 800 mum. Single crystals were grown both unintentionally doped and intentionally doped by means of gas phase dopants. Planar photoconductive diodes were fabricated from the high resistivity crystals and junction diodes were fabricated from the boron-doped crystal layers. The photoconductive diode response was measured and the output signals were analyzed to derive the carrier mobility and lifetime. Combined carrier photoconductive mobility values exceeded 3500 cm2 V-1 s-1, only seen in the best IIa gemstone diamonds. Junction diodes yielded the highest breakdown fields with typical values in excess of 2 x 10(7) V cm-1 dielectric strength.