High-power SiO2∕AlGaN∕GaN metal-oxide-semiconductor heterostructure field-effect transistors

Abstract

We report on SiO 2 / AlGaN / GaN metal-oxide-semiconductor heterostructure field-effect transistors ͑MOSHFETs͒, which exhibit a 6.7 W / mm power density at 7 GHz. Unpassivated and SiO 2-passivated heterostructure field-effect transistors ͑HFETs͒ were also investigated for comparison. Deposited 12 nm thick SiO 2 yielded an increase of the sheet carrier density from 7.6ϫ 10 12 to 9.2ϫ 10 12 cm −2 and a subsequent increase of the static drain saturation current from 0.75 to 1.09 A / mm. The small-signal rf characterization of the MOSHFETs showed an extrinsic current gain cutoff frequency f T of 24 GHz and a maximum frequency of oscillation f max of 40 GHz. The output power of 6.7 W / mm of the MOSHFETs measured at 7 GHz is about two times larger than that of HFETs. The results obtained demonstrate the suitability of GaN-based MOSHFETs for high-power electronics.

Comparison of AlGaN/GaN MSM Varactor Diodes Based on HFET and MOSHFET Layer Structures

“…2 shows the C-V relationship of the MSM-2DEG devices. The capacitance of the HFET MSMs is nearly constant up to the transition voltage of 5 V, which corresponds to the threshold voltage of −4.1 V for HFET transistors in this layer system [8], added by the voltage drop of 1 V of the forwardbiased diode (Fig. 1).…”

“…The capacitance characteristics of the MSM-2DEG based on the MOSHFET structure show large differences compared 8]. Furthermore, the characteristic is asymmetric, i.e., the transition voltage V TRANS depends on the bias polarity.…”

“…Room temperature Hall measurements yield a 2DEG carrier concentration of 7.1 × 10 12 cm −2 and a mobility of 1835 cm 2 /V · s. The MSM-2DEG diodes are fabricated simultaneously with transistor devices to prove the absolute 0741-3106/$20.00 © 2006 IEEE compatibility with HFET technology. The device processing starts with mesa insulation performed by argon sputtering, followed by Ti/Al/Ni/Au ohmic, contact pad, and Ni/Au gate metallization, as described previously [8]. A SiO 2 layer with a nominal thickness of 10 nm is deposited by plasma-enhanced chemical vapor deposition at 300 • C before gate metallization for the MOSHFET-based devices and after gate fabrication for the passivated HFET-based diodes (Fig.…”

AlGaN channel MIS-HEMTs with a very high breakdown electric field and excellent high-temperature performance

“…Besides, the high-frequency performance of AlGaN channel HEMTs has also been investigated [4,12]. Noticeably, although GaN MIS-HEMTs with SiN x [13], SiO 2 [14], HfO 2 [15], ZrO 2 [16], LaAlO 3 [17], etc. as insulators have been proposed to suppress the gate leakage and RF current collapse, enhance breakdown field, and improve interfacial quality, yet AlGaN channel MIS-HEMTs have never been reported.…”

AlGaN/GaN MISHEMTs with AlN gate dielectric grown by thermal ALD technique

“…This effect is also described as dynamic behavior degradation, gate lag, drain lag, etc., which is caused by the charge trapping effect on the AlGaN surface especially in the access region between gate and drain [4][5][6]. In order to solve these two issues, the deposition of oxide-based dielectric such as SiO 2 [7], Al 2 O 3 [8], LaLuO 3 [9], and SrO 2 [10,11] and dielectric stack such as SiN/Al 2 O 3 [12] as gate dielectric layer and passivation layer in the access region simultaneously is widely adopted. But it has been revealed that the introduction of oxide-based dielectric is likely to form Ga-O bond which is thought as one of interface sources leading to current collapse [13].…”