Using high-quality polycrystalline chemical-vapor-deposited diamond films with large grains (∼ 100 μ), field effect transistors (FETs) with gate lengths of 0.1 μ were fabricated. From the RF characteristics, the maximum transition frequency fT and the maximum frequency of oscillation fmax were ∼ 45 and ∼ 120 GHz, respectively. The fT and fmax values are much higher than the highest values for single-crystalline diamond FETs. The dc characteristics of the FET showed a draincurrent density IDS of 550 mA/mm at gate-source voltage VGS of 3.5 V and a maximum transconductancegm of 143 mS/mm at drain voltage VDS of - 8 V. These results indicate that the high-quality polycrystalline diamond film, whose maximum size is 4 in at present, is a most promising substrate for diamond electronic devices.
- Field effect transistor (FET)
- Hydrogen terminated
- Polycrystalline diamond
- RF performance
ASJC Scopus subject areas
- Electrical and Electronic Engineering