Microwave performance evaluation of diamond surface channel FETs

Diamond is expected to become an important semiconductor for high power and high frequency applications. Recent progress in fabrication technology has enabled DC, small signal RF, large signal RF and switching experiments on devices with short gatelength leading to the first comprehensive assessment of the performance capability of these devices. Using high-quality diamond buffer layers the highest cut-off frequencies for L G=0.2 μm namely f T=24.6 GHz, f max(MAG)=63 GHz and f max(U)=80 GHz could be extracted from small signal measurements near the pinch-off region. First noise measurements have resulted in a minimum noise figure F min of approximately 1 dB at 3 GHz. Power measurement at 1 GHz indicate a saturated output power density of 0.35 W/mm, which is, however, limited by the on-wafer tuning range.