Al₂O₃-Passivated Graded-Barrier Al_xGa_1-xN/AlN/GaN/Si Heterostructure Field-Effect Transistor by Hydrogen Peroxide Oxidization Method

Abstract

This letter reports a novel Al 2 O 3 -passivated graded-barrier (GB) Al x Ga 1-x N/AlN/GaN/Si heterostructure field-effect transistor (HFET) formed by using hydrogen peroxide (H 2 O 2 ) oxidization method. Different from the Al 0.26 Ga 0.74 N conventional barrier (CB), a compositionally graded Al x Ga 1-x N (x = 0.22∼0.3) barrier was devised to increase the Schottky-barrier height ( B ) and improve the interfacial quality at the same time. Reduced gate leakage and enhanced device gain are further achieved by the Al 2 O 3 passivation. The present Al 2 O 3 -passivated/unpassivated GB-HFETs (unpassivated CB-HFET) has demonstrated improved maximum drain-source current density (I DS, max ) of 708/699 (654) mA/mm at V DS = 7 V, maximum extrinsic transconductance (g m, max ) of 139/126 (113) mS/mm, subthreshold swing (SS) of 176/253 (274) mV/dec, on/off-current ratio (I on /I off ) of 3.8 × 10 6 /1.4 × 10 4 (7.1 × 10 3 ), two-terminal off-state gate-drain breakdown voltage (BV GD ) of −126.4/−96.8 (−89.3) V, turn-on voltage (V on ) of 1.1/0.7 (0.3) V, and three-terminal on-state drain-source breakdown voltage (BV DS ) of 109/89 (71) V.

Comparative Study on Graded-Barrier AlxGa1−xN/AlN/GaN/Si Metal-Oxide-Semiconductor Heterostructure Field-Effect Transistor by Using Ultrasonic Spray Pyrolysis Deposition Technique

“…Thus, the USPD treatment was set to be 30 s for samples C-D. As shown in the inset of figure 1, the TEM photo of the MOS-gate structure shows that the corresponding oxide thickness is about 15 nm. In order to study the interface property, the gate-lag characteristics were measured for samples C-D at 300 K, as shown in figure 3 Δ CC was characterized to be 11% (12%) for sample D (C), which was superior to 31% (32%) of sample B (A) and 20% of the oxide-passivated GB HFET using H 2 O 2 oxidization method as studied in our previous work [15]. This indicates the interface was effectively improved by the oxide passivation formed by using USPD.…”

“…This indicates the interface was effectively improved by the oxide passivation formed by using USPD. As compared with oxide-passivated GB HFET [15], complete oxide coverage on the barrier surface between source and drain electrodes was obtained by the MOS-gate design. The decreased Al-ratio of the GB design near gate in sample D has further improved the barrier/channel interface and reduced the Δ CC deviation, as compared to the CB structure in sample C. Enhanced I DS performance can therefore be expected in sample D, as will be discussed later.…”

“…All four devices were fabricated at the same time, except for the oxide deposition. Device processing and fundamental characterizations for the reference samples A-B with Schottky-gate structures was described in our previous work [15]. For the device fabrications of samples C-D, the device isolation was obtained by performing mesa etching using an inductively coupled-plasma reactive ion etcher (ICP-RIE).…”

“…Various gate oxides were also applied to MOS-HFETs, including Al 2 O 3 [9], NiO [10], MgO [11], SiO 2 [12], ZrO 2 [13], and TiO 2 [14]. Our previous work has [15] reported an oxide-passivated graded-barrier (GB) Al x Ga 1−x N/AlN/GaN HFET grown on an Si substrate by using the hydrogen peroxide oxidization method. The Al-composition of the AlGaN barrier near the gate was increased to enhance the Schottky barrier height (Φ B ).…”

Comparative Study of AlGaN/AlN/GaN Metal-Oxide-Semiconductor High Electron Mobility Transistors with Ni/Au Gate Electrode

“…The one is aluminum oxide (Al 2 O 3 ), which has a high dielectric constant (9) and a wide band gap (8.8 eV). 12,13 The other is the nickel oxide (NiO) having also high dielectric constant (11.9) and appropriate band gap (3.6 ∼ 4.0 eV). 14,15 For the insertion of a high dielectric constant of gate insulator between gate metal and GaN layer, an MOS-type gate structure will be formed to suppress the gate leakage current, enhance the drain current, and induce a positive shift in threshold voltage.…”