Analysis of electrical properties of insulators (Si₃N₄, SiO₂, AlN, and Al₂O₃)/0.5 nm Si₃N₄/AlGaN/GaN heterostructures

Abstract

The electrical properties in AlGaN/GaN heterostructures with Si-and Al-based insulators (Si 3 N 4 , SiO 2 , AlN, and Al 2 O 3 ) have been examined and analyzed. By insulators deposition, significant increase in the two-dimensional electron gas (2DEG) density (N s ) was observed with the order ofAs the result, the decrease in the sheet resistance (R) was observed; the smallest order of R was R(Al 2 O 3 ) < R(AlN) < R(Si 3 N 4 ) < R 0 ~ R(SiO 2 ) (R 0 : R without insulator). The insulators deposition effect has thus been shown to be significant and different among insulators. The increase in N s was analyzed in terms of the change in the potential profile, and the observed differences in N s among insulators have been interpreted. The band engineering including insulators is indispensable in understanding and designing AlGaN/GaN HFETs, since insulators are commonly used for the surface passivation as well as for the gate insulators, and the insulators deposition is to alter the essential device parameters such as the source resistance. . In these devices, insulators have proved to be very important constituent materials, because (i) the surface passivation by insulators is commonly used to suppress the current collapse effect, which is specific to AlGaN/GaN HFETs [2], and (ii) the insulated-gate HFETs or the metal-insulator-semiconductor (MIS) HFETs [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] are shown to be effective to reduce the large gate leakage current, which is generally observed in AlGaN/GaN HFETs.Insulators thus play very important roles in AlGaN/GaN HFETs, and hence, understanding the electrical properties of AlGaN/GaN heterostructures with insulators is one of the most fundamental issues to be addressed in understanding and designing the device performance. From this point of view, we have examined the deposition effect of insulators on the electrical properties, and theoretically analyzed the results in terms of the potential profile of the heterostructures with insulators. We have examined the effect for Si-and Al-based insulators (Si 3 N 4 , SiO 2 , AlN, and Al 2 O 3 ,) to systematically understand the effect.

Continuous flow supercritical water synthesis and crystallographic characterization of anisotropic boehmite nanoparticles

“…It is used as a catalyst support and as a precursor for the production of alumina, Al 2 O 3 . Alumina is widely used in catalysis applications, as well as for thermal and electrical insulation (Doskocil & Mueller, 2005;Osaki et al, 1998;Chang et al, 2008;Maeda et al, 2007). Boehmite is an adsorbent (Hota et al, 2008), and the energy consuming and water vapour producing phase transition from boehmite to alumina also makes the material a potential fire retardant (Camino et al, 2001).…”

Electrical and structural properties of AlN/GaN and AlGaN/GaN heterojunctions

“…1,2 The high 2DEG concentration is achieved because of the presence of a strong piezoelectric field and this concentration increases with increasing Al mole fraction in the solid solution. 3,4 Another potential advantage is the decrease in the gate leakage in AlN/GaN HEMT structures compared to AlGaN/GaN HJs. 3,4 Another potential advantage is the decrease in the gate leakage in AlN/GaN HEMT structures compared to AlGaN/GaN HJs.…”

“…1 Ideally, using AlN barriers instead of AlGaN barriers should yield the best results in terms of the 2DEG density and the experimental studies show that the 2DEG concentration in AlN/GaN HJs is almost twice higher than those in their AlGaN/GaN counterparts although one also usually observes some deterioration of the 2DEG mobility. Although successful fabrication of AlN/GaN HEMTs has been reported in several papers, 3,4 little is known about the current flow mechanisms and deep traps in AlN/GaN HJs. Although successful fabrication of AlN/GaN HEMTs has been reported in several papers, 3,4 little is known about the current flow mechanisms and deep traps in AlN/GaN HJs.…”

Metastable centers in AlGaN/AlN/GaN heterostructures

“…The total 2DEG depletion voltage (the voltage at which capacitance stops decreasing due to the removal of electrons from the 2DEG region for voltage sweeps from positive to negative bias or starts increasing for sweeps of the opposite direction; it is closely related with the transistor threshold voltage) monotonically increases with Al composition in the AlGaN barrier from 20% to 40% and then drops dramatically almost to the 20% Al level for Al composition of 50 at. 10,16,17 The results of low temperature C-V measurements carried out on samples cooled at various voltages and the effect of illumination at low temperature on these characteristics confirm this hypothesis and shed additional light on the properties of the centers in question. It is instructive to compare the data in Fig.…”