Wafer-level MOCVD growth of AlGaN/GaN-on-Si HEMT structures with ultra-high room temperature 2DEG mobility

Abstract

In this work, we investigate the influence of growth temperature, impurity concentration, and metal contact structure on the uniformity and two-dimensional electron gas (2DEG) properties of AlGaN/GaN high electron mobility transistor (HEMT) structure grown by metal-organic chemical vapor deposition (MOCVD) on 4-inch Si substrate. High uniformity of 2DEG mobility (standard deviation down to 0.72%) across the radius of the 4-inch wafer has been achieved, and 2DEG mobility up to 1740.3 cm2/V⋅s at room temperature has been realized at low C and O impurity concentrations due to reduced ionized impurity scattering. The 2DEG mobility is further enhanced to 2161.4 cm2/V⋅s which is comparable to the highest value reported to date when the contact structure is switched from a square to a cross pattern due to reduced piezoelectric scattering at lower residual strain. This work provides constructive insights and promising results to the field of wafer-scale fabrication of AlGaN/GaN HEMT on Si.

Temperature-Dependent Thermal Boundary Conductance of Monolayer MoS2 by Raman Thermometry

“…MoS2 films were directly grown by chemical vapor deposition 16 (CVD, see Methods) onto thin SiO2 (Figure 1a) and AlN 17 their temperature dependence around room temperature. The thermal conductivity of doped silicon can be expressed as kSi ≈ 3×10 4 /T Wm -1 K -1 , the thermal conductivity of SiO2 is kSiO2 ≈ ln(T 0.52 ) -1.6 Wm -1 K -1 (where T is in Kelvin) and the TBC between the two is GSi-SiO2 ≈ 600…”

“…The 185 nm thick AlN was grown by MOCVD on the Si substrate immediately after an HF dip to remove the native oxide. The dislocation density in the AlN film is expected to be ∼10 9 cm –2 due to the lattice mismatch and polarity difference . The MoS 2 was deposited by CVD at 850 °C directly on the AlN, in a process similar to the one described in refs and .…”

“…The dislocation density in the AlN film is expected to be ~ 10 9 cm -2 due to the lattice mismatch and polarity difference. 17 The MoS2 was deposited by CVD at 850 °C directly on the AlN, in a process similar to the one described in Refs. 16 and 18.…”

Deep Ultraviolet Luminescence Due to Extreme Confinement in Monolayer GaN/Al(Ga)N Nanowire and Planar Heterostructures

“…Deep-ultraviolet (UV) light sources are important for high density-optical storage, artificial photosynthesis, and water purification, in addition to solid-state lighting. − The conventional technique is to fabricate devices with AlN, high Al-containing AlGaN alloys, and quantum wells (QWs) using these materials. − In addition to problems associated with p-doping, light emission from these materials along the c -plane is extremely weak, as opposed to GaN. The preferred emission direction is from the a -plane due to differences in the valence bandstructure between AlN and GaN. ,,, In principle, emission in the deep-UV wavelengths can also be obtained from GaN layers of thickness 1–2 atomic monolayers (MLs), sandwiched by AlN or AlGaN barrier layers.…”

Electron beam irradiation of gallium nitride-on-silicon betavoltaics fabricated with a triple mesa etch

“…The growth details of this buffer structure have been described previously. 16 To create the nand p-type regions, the GaN was doped during growth with silicon and magnesium, respectively. Because GaN has a natural tendency towards unintentional n-type doping as result of the donor-like behavior, the i-region was lightly counterdoped with Mg. Based on the simulations results and comparison with existing literature, the p-GaN region had a thickness of 80 nm with a dopant concentration of 4 x 10 17 cm -3 , the i-GaN region had a thickness of 600 nm with a dopant concentration of 1 x 10 15 cm -3 , and the n-GaN region had a thickness of 80 nm with a dopant concentration of 3 x 10 18 cm -3 .…”