Abstract
We have epitaxially stabilized a series of monoclinic (AlxGa1-x-yIny)2O3 alloys by careful choice of molecular beam epitaxy growth conditions, which balance alloy growth with suboxide desorption. The films are pseudomorphic to (010) ..beta..-Ga2O3 substrates at thicknesses up to 150 nm with compositions ranging from (Al0.01Ga0.83In0.16)2O3 to (Al0.24Ga0.75In0.03)2O3. The absorption edge shifts from approximately 4.62-5.14 eV with coincidently increasing Al and decreasing In mole fractions. J-V measurements reveal an increase in resistivity over four orders of magnitude with a maximum value of 4.2 x 105 ..omega..-cm for (Al0.17Ga0.76In0.07)2O3, which has nearly identical lattice parameters (both in-plane and out-of-plane) to the underlying ..beta..-Ga2O3. Scanning transmission electron microscopy of this sample reveals a mostly uniform and single crystalline film, though we identify areas of non-uniform In incorporation and some ..gamma..-phase inclusions. This work demonstrates the feasibility of thick layers lattice-matched to ..beta..-Ga2O3 with increased bandgap compared to phase-separation limited (Al,Ga)2O3. These alloys can enable higher bandgap epitaxial dielectrics and high sheet charge density transistors by increasing the conduction band offset with respect to ..beta..-Ga2O3.
| Original language | American English |
|---|---|
| Number of pages | 8 |
| Journal | Applied Physics Letters |
| Volume | 125 |
| Issue number | 17 |
| DOIs | |
| State | Published - 2024 |
NREL Publication Number
- NREL/JA-5K00-91276
Keywords
- band gap
- chemical properties
- crystal structure
- electronic band structure
- epitaxy
- optical absorption
- oxides
- surface and interface chemistry
- transistors
- transmission electron microscopy