Improved mobility in InAlN/AlGaN two-dimensional electron gas heterostructures with an atomically smooth heterointerface

Abstract

An InAlN/AlGaN two-dimensional electron gas (2DEG) heterostructure with an "regrown AlN initial layer" was grown on AlN/sapphire template by metalorganic chemical vapor deposition, and their structural and electrical properties were investigated. It was confirmed that the prepared sample had an atomically-smooth heterointerface and exhibited an improved 2DEG mobility of 242 cm 2 /Vs compared to the sample without the regrown AlN layer.

Two-dimensional WS2/MoS2 heterostructures: properties and applications

“…Two-dimensional (2D) materials have been one of the most widely scientifically investigated subjects because a number of uncommon physical events arise when thermoelectric interaction is limited to a plane. [1][2][3] van der Waals (vdWs) heterostructures composed of layered materials have attracted extensive focus due to their superb properties such as smooth heterostructure interface, 4,5 ultrafast carrier transport, 6 and highly gate-tunable bandgap. [7][8][9] With the continuous development of 2D material fabrication technology, transition metal dichalcogenides (TMDs) have been studied in more detail.…”

High drain-current-density and high breakdown-field Al0.36Ga0.64N-channel heterojunction field-effect transistors with a dual AlN/AlGaInN barrier layer

“…22) To date, our past research on AlGaN-channel heterostructures and HFETs have mostly been conducted for Al x Ga 1−x N channels with x around 0.2. 17,[19][20][21][22] Regarding AlGaNchannel 2DEG heterostructures and HFETs, we predict that higher-AlN-mole-fraction Al x Ga 1−x N channels with x around 0.4 may cause a little lower 2DEG mobilities 16) but much higher breakdown fields [1][2][3]21,22) compared with those with x around 0.2 that we have ever studied. Therefore, in this study, we attempted to fabricate AlGaInN/AlGaN HFETs with x around 0.4 adopting the SAG contacts.…”

“…The heterostructure consists of a 2 μm thick Al 0.36 Ga 0.64 N channel layer and a 1.5 nm thick AlN/20 nm thick Al 0.845 Ga 0.15 In 0.005 N dual barrier layer, which was grown on an epitaxial AlN/sapphire template by MOCVD. [15][16][17][19][20][21][22][23][24][25] In accordance with the design concept described in our previous report, 20) the alloy composition of the quaternary AlGaInN barrier layer was designed to have a lattice strain of no more than 0.6% in the in-plane tensile direction and a 2DEG density higher than 1.5 × 10 13 cm −2 . For comparison, we also prepared another heterostructure sample for HFETs without the top AlN barrier layer.…”

“…For the past several years, the authors have conducted intensive research on the growth of AlGaNchannel two-dimensional electron gas (2DEG) heterostructures by metalorganic chemical vapor deposition (MOCVD) and their application to HFETs. [15][16][17][18][19][20][21][22][23] Most notable topic in our past research is the proposal of strain-controlled quaternary AlGaInN barrier layers. [20][21][22][23] That is, the quaternary AlGaInN barrier layers properly designed and grown can provide smooth surface morphologies and thermal stability in addition to high 2DEG densities 20) and thereby contributed to the improvement in the device performance.…”

Design and material growth of AlGaN-channel two-dimensional-electron gas heterostructures employing strain-controlled quaternary AlGaInN barrier layers

“…19) Then, it was confirmed that 2DEG mobility for an AlInN/AlGaN heterostructure was improved with an atomically smooth heterointerface. 20) In addition to these, AlInN/AlGaN HFETs were fabricated and their electrical characteristics including offstate breakdown voltages were evaluated. Eventually, our theoretical analyzes have predicted that AlGaN-channel HFETs can show higher device performance than in conventional AlGaN/GaN HFETs with an optimized field-plate electrode by achieving an ohmic contact resistance lower than 1 × 10 −5 Ω cm 2 .…”