Demonstration of AlGaN/GaN HEMTs on vicinal sapphire substrates with large misoriented angles

Abstract

In this work, the electrical characteristics of AlGaN/GaN high-electron-mobility transistors (HEMTs) on vicinal c-plane sapphire substrates with different misoriented angles are investigated. As the angle increases from 0.2°, 1.0° to 4.0°, an enlarged width and height of surface step bunching as well as significantly enhanced electron mobility from 957, 1123 to 1246 cm2/V s were measured. As a result, a large boost in the maximum output current (IDmax) from ∼300 mA/mm (on a 0.2° substrate) to ∼650 mA/mm (on a 4.0° substrate) can be observed. Importantly, HEMTs on 1.0° and 4.0° substrates exhibit an obvious anisotropic electrical behavior: the IDmax along the [11-20] orientation is larger than that along the [10-10] orientation. Such a difference becomes more distinct as the misoriented angle increases, attributing to the lifted step height that would introduce a potential barrier for the electron transport along the [10-10] orientation. In short, this work demonstrates an effective approach toward the realization of high-performance HEMTs with anisotropic electrical behavior on a single device platform.

Normally-OFF AlGaN/GaN-based HEMTs with decreasingly graded AlGaN cap layer

“…* Author to whom any correspondence should be addressed. two-dimensional electron gases (2DEGs) at the AlGaN/GaN hetero-interface [4][5][6]. As a result, such devices have emerged as competitive candidates in various applications such as electric vehicles, wireless communication, data centre, etc [7].…”

Adaptive wind-evoked power devices for autonomous motor control applications

“…Due to their excellent semiconductor and piezoelectric properties, III-nitride materials (e.g., GaN and AlN) and their alloys are extremely promising for future power electronics. [15][16][17][18][19] Thanks to its high mobility, high carrier density, and large breakdown field, the AlGaN/AlN/GaN high electron mobility transistor (HEMT) is one of the best candidates for power and radiofrequency devices. 20 Based on the strong piezoelectric characteristics of GaN and AlN, the two-dimensional electron gas (2DEG) density can be modulated by the piezoelectric polarization charges generated at the AlGaN/AlN/GaN heterointerfaces under external stress.…”

Origins of the Schottky Barrier to a 2DHG in a Au/Ni/GaN/AlGaN/GaN Heterostructure

“…This equation explains why the sheet hole density and mobility track each other oppositely (Figure (d)), when extracted via this method with a relative immunity to thickness of u-GaN (between 16 and 30 nm). The sheet hole density at the GaN/AlGaN interface can be confirmed by using C – V characteristics . To study current transport through the contact, temperature dependent I – V s at a gap length of 5 nm, for an 18 nm thick u-GaN, are reported in (Figure S1).…”

“…The sheet hole density at the GaN/AlGaN interface can be confirmed by using C−V characteristics. 22 To study current transport through the contact, temperature dependent I−Vs at a gap length of 5 nm, for an 18 nm thick u-GaN, are reported in (Figure S1). The SB, Φ B , can be extracted from a semilog plot of I−V as depicted in Figure 3(a) as…”

“…The sheet hole density at the GaN/AlGaN interface can be confirmed by using C – V characteristics. 22 To study current transport through the contact, temperature dependent I – V s at a gap length of 5 nm, for an 18 nm thick u-GaN, are reported in ( Figure S1 ). The SB, Φ B , can be extracted from a semilog plot of I – V as depicted in Figure 3 (a) as where I S = AA * T 2 e – qΦ B / kT ; n , the diode ideality factor, is obtained from the slope; and the SB, Φ B , can be obtained from the intercept, I s , as …”