High f _T and f _MAX for 100 nm unpassivated rectangular gate AlGaN/GaN HEMT on high resistive silicon (111) substrate

Abstract

A high current gain cutoff frequency ( f T ) of 90 GHz and a peak maximum oscillation frequency ( f MAX ) as high as 150 GHz are reported for a rectangular-shaped gate AlGaN/GaN high-electron mobility transistor (HEMT) on a high resistive silicon (HR-Si) substrate. The combined high f T /f MAX values for 100 nm unpassivated gate device demonstrate the high-quality heterostructure on silicon substrate. The reported high-performance RF device characteristics are comparable and even superior to the existing passivated AlGaN/ GaN HEMTs of similar gate length. In addition, good DC characteristics have been recorded with the drain current density and an extrinsic transconductance of 0.6 A/mm and 157 mS/mm, respectively.Introduction: With the remarkable combination of superior physical properties and highly scaled device geometries, GaN-based highelectron mobility transistors (HEMTs) remain a good choice of device for high-power, wideband and high-temperature applications [1,2]. The high breakdown field, high-electron saturation velocity and large sheet carrier densities together with the implementation of short gate geometries (i.e. L g < 0.1 μm) make the GaN system the leading contender for solid-state power amplifiers at the microwave-and millimetrewave frequency range (30-300 GHz) [3][4][5]. Compared with the mature GaN technology on sapphire and SiC substrates, the handling of high power densities of GaN on the high resistive silicon (HR-Si) substrate promises a low-cost solution, provided the high-quality device grade GaN heterostructure is realised.The emerging reports on the millimetre-wave frequency performances of AlGaN/GaN-based HEMTs showcase the high-frequency solution of GaN on Si. For example, a fully passivated 75 nm gate AlGaN/GaN HEMT on Si demonstrates that a high f T /f MAX = 152/149 GHz with a large signal operation yields an output power of 2 W/mm at 40 GHz [6]. An attractive RF performance has been reported for GaN on Si with f T /f MAX = 100/206 GHz for a T-shaped 90 nm gate length [7]. A similar gate geometry AlGaN/GaN HEMT with the incorporation of a AlGaN back barrier yielding a high breakdown voltage (BV = 100 V) and a high f MAX of 226 GHz with a simultaneous f T of 63 GHz has been reported for L g = 160 nm [8]. It is obvious that the enhancement of f T / f MAX for the AlGaN/GaN HEMT is still a major concern although high f MAX has been achieved for highly scaled devices with SiN passivation. Only a few reports have been published for 0.1 μm gate AlGaN/ GaN HEMT technology exhibiting high f T /f MAX with passivation [9, 10]. Hence, further performance enhancement for millimetre-wave applications warrants the implementation of deeply scaled devices which involves complicated gate geometries and process techniques.In this Letter, we report a simple AlGaN/GaN HEMT heterostructure with a rectangular shaped 0.1 μm gate demonstrating good performance in both the DC and the RF regimes.

Enhancement- and depletion-mode AlGaN/GaN HEMTs on 3C-SiC(111)/Si(111) pseudosubstrates

“…Comparison of the cutoff frequencies of our E‐mode tri‐gate and D‐mode planar GaN/Al 0.2 Ga 0.8 N/AlN/GaN HEMTs on Si with our last results and with the best f T data reported by other groups for AlGaN/GaN HEMTs on Si and on SiC .…”

Performance improvement in NiO x -based GaN MOS-HEMTs

“…The comparison is performed at the same gate voltage. In this work, gate leakage current density of 1 × 10 −5 A cm −2 is found for NiO x (7.2 nm), which are comparable to ALD deposited dielectric [47][48][49][50][51][52][53][54][55][56][57][58]. To further investigate the scalability of the oxide HEMTs, the f T × L g product is plotted as a function of L g and compared with previously reported values in figure 10 for scalable technology without sacrificing high-frequency behavior.…”