Application of Sputtering-Deposited AlN Films to Gate Dielectric for AlGaN/GaN Metal–Insulator–Semiconductor Heterojunction Field-Effect Transistor

Abstract

AlN films deposited by RF magnetron sputtering are applied to AlGaN/GaN metal–insulator–semiconductor heterostructure field-effect transistors (MIS-HFETs) as a gate dielectric. X-ray photoelectron spectroscopy (XPS) was used to characterize the AlN films, showing their chemical bonds and the bandgap by N 1s electron energy loss spectroscopy. The AlGaN/GaN MIS-HFET with a gate length of 150 nm was successfully fabricated, exhibiting low gate leakage currents for both reverse and forward biases, which are at least four orders of magnitude lower than those of reference Schottky-HFETs. Although these results support the possibility of sputtering-deposited AlN as a gate insulator, there are AlN/AlGaN interface states unfavorable for device performance, which were investigated by the frequency dispersion in the capacitance–voltage (C–V) characteristics.

AlGaN/GaN devices with metal–semiconductor or insulator–semiconductor interfacial layers: Vacuum level step due to dipole and interface fixed charge

“…6 On the other hand, in the case of the MIS devices, V th is affected by the insulator-semiconductor conduction band offset w and the fixed charge density σ int of the insulator-semiconductor interface. Various insulators such as oxides Al 2 O 3 , 7 HfO 2 , 8,9 TiO 2 , 10 AlSiO, 11,12 AlTiO, [13][14][15][16][17][18][19] oxynitrides TaON, 20 AlON, 21 and nitrides BN, 22,23 AlN [24][25][26][27][28] have been employed as a gate insulator for GaN-based devices, where V th can be modulated by both w and σ int . Similarly to f S , w is not uniquely determined by the electron affinity difference between the insulator and the semiconductor, and is affected by insulator-semiconductor interface treatments.…”

Low-frequency noise in AlTiO/AlGaN/GaN metal-insulator-semiconductor field-effect transistors with non-gate-recessed or partially-gate-recessed structures

“…For high-speed and high-power applications, GaN-based metal-insulator-semiconductor field-effect transistors (MIS-FETs) have been extensively investigated using various gate insulators, such as high-dielectric-constant (high-k) oxides Al 2 O 3 [1], HfO 2 [2,3], TiO 2 [4], AlSiO [5,6], AlTiO [7][8][9][10][11][12], high-k oxynitrides TaON [13], AlON [14], and high-k nitrides BN [15,16], AlN [17][18][19][20][21]. In particular, Al x Ti y O (AlTiO), an alloy of Al 2 O 3 and TiO 2 , is an important insulator, because it can be applied to dielectric constant engineering, energy gap engineering, and interface charge engineering [11].…”

Recent progress in III-nitride nanosheets: properties, materials and applications

“…Bulk III-nitrides, including gallium nitride (GaN), aluminium nitride (AlN), indium nitride (InN) and their alloys, present brilliant properties, such as high carrier mobility [30][31][32], high breakdown voltage [33][34][35], and a large absorption coefficient [36,37], demonstrating wide applications [38] in luminescent material [39][40][41][42], field-effect transistors (FETs) [43][44][45][46] and high-efficiency solar cells [47,48]. As III-nitrides have been drawing increased attention from researchers, their two dimensional structures, e.g.…”