Demonstration of β-(AlxGa1-x)2O3/Ga2O3 double heterostructure field effect transistors

Abstract

In this work, we demonstrate modulation-doped β-(AlxGa1-x)2O3/Ga2O3 double heterostructure field effect transistors. The maximum sheet carrier density for a two-dimensional electron gas (2DEG) in a β-(AlxGa1-x)2O3/Ga2O3 heterostructure is limited by the conduction band offset and parasitic channel formation in the barrier layer. We demonstrate a double heterostructure to realize a β-(AlxGa1-x)2O3/Ga2O3/(AlxGa1-x)2O3 quantum well, where electrons can be transferred from below and above the β-Ga2O3 quantum well. The confined 2DEG charge density of 3.85 × 1012 cm−2 was estimated from the low-temperature Hall measurement, which is higher than that achievable in a single heterostructure. Hall mobilities of 1775 cm2/V·s at 40 K and 123 cm2/V·s at room temperature were measured. Modulation-doped double heterostructure field effect transistors showed a maximum drain current of IDS = 257 mA/mm, a peak transconductance (gm) of 39 mS/mm, and a pinch-off voltage of −7.0 V at room temperature. The three-terminal off-state breakdown measurement on the device with a gate-drain spacing (LGD) of 1.55 μm showed a breakdown voltage of 428 V, corresponding to an average breakdown field of 2.8 MV/cm. The breakdown measurement on the device with a scaled gate-drain spacing of 196 nm indicated an average breakdown field of 3.2 MV/cm. The demonstrated modulation-doped β-(AlxGa1-x)2O3/Ga2O3 double heterostructure field effect transistor could act as a promising candidate for high power and high frequency device applications.

Band Offsets at κ-([Al,In]xGa1–x)2O3/MgO Interfaces

“…The same then holds true for the orthorhombic modification of Ga2O3 only with even higher expected sheet charge carrier densities at the interfaces to κ-(InxGa1-x)2O3 or κ-(AlxGa1-x)2O3. HEMT structures and quantum wells containing 2DEGs are also possible in the monoclinic modification [12][13][14][15][16][17] . However, they always require a delta-doped layer containing e.g.…”

Hydrogen plasma treatment of β -Ga2O3: Changes in electrical properties and deep trap spectra

“…[1][2][3][4] Ternary solid solutions of (Al x Ga 1Àx ) 2 O 3 compatible with binary Ga 2 O 3 have been developed for use in high electron mobility transistor (HEMT) applications. 5 Advances in Ohmic contact preparation, Schottky diode fabrication, and dielectric film deposition have been reported. [1][2][3] However, issues remain; among them is the behavior of various impurities in b-Ga 2 O 3 .…”

Device processing and junction formation needs for ultra-high power Ga2O3 electronics

“…For rf applications, it is hard to see where Ga 2 O 3 brings advantages, although gate-allaround FinFETs can operate in accumulation mode in the on state. [25] Additionally, for lateral devices, the (Al x Ga 1−x ) 2 O 3 / Ga 2 O 3 heterostructure has been recently demonstrated using modulation doping of the barrier layer, [26][27][28][29][30] as β-Ga 2 O 3 is nonpolar. There needs to be a major breakthrough, such as a >5 kV transistor or Ga 2 O 3 on diamond HFETs.…”

“…5, the use of (Al x Ga 1−x ) 2 O 3 twodimensional electron gas (2DEG) channels allows high carrier density and mobility (high on-state driving current) and fast switching speed. [26][27][28][29][30] All of the devices benefit from the addition of field plates to tailor the electric field profile, although multiple field plates have yet to be implemented and this might improve the dynamic on-resistance in FETs. Current collapse phenomena have been observed in MOSFETs but not studied to the extent they have in AlGaN/GaN HEMTs.…”