1f:T521,The potential of SiC and diamond for producing microwave and millimeter-wave electronic devices is reviewed. It is shown that both of these materials possess characteristics that may permit RF electronic devices with performance similar to or greater than what is available from devices fabricated from the commonly used semiconductors, Si, GaAs, and InP. Theoretical calculations of the RF performance potential of several candidate high-frequency device structures are presented: the metal semiconductor field-effect transistor (MESFET), the impact avalanche transit-time (IMPATT) diode, and the bipolar junction transistor (BJT). Diamond MESFETs are capable of producing over 200 W of X-band power as compared to about 8 W for GaAs MESFETs. Devices fabricated from SiC should perform between these limits. Diamond and SiC IMPATT diodes also are capable of producing improved RF power compared to Si, GaAs, and InP devices at microwave frequencies. RF performance degrades with frequency and only marginal improvements are indicated at millimeter-wave frequencies. Bipolar transistors fabricated from wide bandgap material probably offer improved RF performance only at UHF and low microwave frequencies.< >20:T4eb,Using high-quality polycrystalline chemical-vapor-deposited diamond films with large grains (/spl sim/100 μm), field effect transistors (FETs) with gate lengths of 0.1 μm were fabricated. From the RF characteristics, the maximum transition frequency f _T and the maximum frequency of oscillation f _max were /spl sim/ 45 and /spl sim/ 120 GHz, respectively. The f _T and f _max values are much higher than the highest values for single-crystalline diamond FETs. The dc characteristics of the FET showed a drain-current density I/sub DS/ of 550 mA/mm at gate-source voltage V/sub GS/ of -3.5 V and a maximum transconductance g/sub m/ of 143 mS/mm at drain voltage V/sub DS/ 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.

	Year	Citations

References