AlGaN/GaN metal oxide semiconductor heterostructure field effect transistor

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251

134

We report on a metal–insulator–semiconductor heterostructure field-effect transistor (MISHFET) using Si3N4 film simultaneously for channel passivation and as a gate insulator. This design results in increased radio-frequency (rf) powers by reduction of the current collapse and it reduces the gate leakage currents by four orders of magnitude. A MISHFET room temperature gate current of about 90 pA/mm increases to only 1000 pA/mm at ambient temperature as high as 300 °C. Pulsed measurements show that unlike metal–oxide–semiconductor HFETs and regular HFETs, in a Si3N4 MISHFET, the gate voltage amplitude required for current collapse is much higher than the threshold voltage. Therefore, it exhibits significantly reduced rf current collapse.

mentioning

confidence: 99%

Si 3 N 4 / AlGaN/GaN –metal–insulator–semiconductor heterostructure field–effect transistors

Koudymov

Simin

et al. 2001

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251

134

“…4,5 This approach allowed us to fabricate devices with dc and rf characteristics similar to those for conventional AlGaN/GaN HFETs, however, with approximately 6 orders of magnitude lower gate leakage currents. Despite much lower gate leakage currents, the MOSHFET design has not yet solved the aging, current slump, and large contact resistance problems.…”

mentioning

confidence: 99%

“…The maximum cutoff frequency times the gate length product is as high as 11.6 GHz m. The measured maximum f t and f max values are comparable with identical geometry conventional AlGaN/GaN HFETs and MOSHFET devices. 4 Microwave power performance of the 200 m wide GaN HDMESFETs with channel doping of 1.5 ϫ10 18 cm Ϫ3 at 2 GHz was investigated in continuous wave ͑cw͒ and pulsed measurement regimes. The pulsed rf was measured using 20 m drain voltage pulses with time between pulses 7.8 ms.…”

mentioning

confidence: 99%

Highly doped thin-channel GaN-metal–semiconductor field-effect transistors

Gaška

Shur

et al. 2001

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We report on the influence of the channel doping on dc, high frequency, and noise performance of GaN metal–semiconductor field-effect transistors (MESFETs) grown on sapphire substrates. The devices with the channel thicknesses from 50 to 70 nm and doping levels up to 1.5×1018 cm−3 were investigated. An increase in the channel doping results in the improved dc characteristics, higher cutoff, and maximum oscillation frequencies, and reduced low frequency and microwave noise. The obtained results demonstrate that the dc and microwave performance characteristics of short-channel GaN MESFETs may be comparable to those for conventional AlGaN/GaN heterostructure FETs.

“…The leakage current was further reduced by surface passivation of the devices using plasma enhanced chemical vapor deposited ͑PECVD͒ SiO 2 layer. This SiO 2 deposition technique recently has been used by us to fabricate extremely low leakage current, high transconductance metal-oxidesemiconductor heterojunction field-effect transistors ͑HFETs͒ on sapphire 5 and SiC substrates. 6 The epilayer structure for our devices consisted of a 1.2-m-thick layer of n Ϫ -GaN, which was deposited over basal plane sapphire substrates at 1000°C and 76 Torr using low pressure metalorganic chemical vapor deposition.…”

Section: Author(s)mentioning

confidence: 99%

“…The growth conditions and precursors are identical to those reported in our previous work. 5 The room temperature carrier density for the active n-GaN layer was 3ϫ10 16 cm Ϫ3 . Our devices consisted of the lateral geometry transparent Schottky barriers surrounded by annular ohmic contacts ͑see inset in Fig.…”

Section: Author(s)mentioning

confidence: 99%

SiO 2 -passivated lateral-geometry GaN transparent Schottky-barrier detectors

Adivarahan

Simin

Yang

et al. 2000

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103

We report on a transparent Schottky-barrier ultraviolet detector on GaN layers over sapphire substrates. Using SiO2 surface passivation, reverse leakage currents were reduced to a value as low as 1 pA at 5 V reverse bias for 200 μm diameter device. The device exhibits a high internal gain, about 50, at low forward biases. The response time (about 15 ns) is RC limited, even in the internal gain regime. A record low level of the noise spectral density, 5×10−23 A2/Hz, was measured at 10 Hz. We attribute this low noise level to the reduced reverse leakage current.