Epitaxial growth and interface band alignment studies of all oxide α-Cr2O3/β-Ga2O3 p-n heterojunction

Abstract

Epitaxial growth of α-Cr2O3(p-type) on c-Al2O3 and β-Ga2O3 (n-type) on α-Cr2O3(p-type) has been carried out to make an all oxide epitaxial n-type β-Ga2O3/p-type α-Cr2O3 heterojunction using RF sputtering. A valence band offset of 3.38 ± 0.2 eV at the heterojunction is determined using Kraut's method. From the bandgap measurements of α-Cr2O3 and β-Ga2O3, the conduction band offset of 1.68 ± 0.2 eV at the heterojunction is obtained. Thus, the band alignment at this heterojunction is found to be staggered (Type-II), which leads to the confinement of electrons and holes in the β-Ga2O3 layer and α-Cr2O3 layer, respectively. Our results provide a pathway to design all oxide optoelectronic devices based on a p-n heterojunction consisting of n-type β-Ga2O3 and p-type α-Cr2O3.

A Strategic Review on Gallium Oxide Based Deep‐Ultraviolet Photodetectors: Recent Progress and Future Prospects

“…The heterojunction between n‐type β‐Ga 2 O 3 and p‐type α‐Cr 2 O 3 was found to be a staggered type alignment leading to a confinement of electrons in the former and electrons in the latter. [ 203 ] For others, ZnO/β‐Ga 2 O 3 was found to have type II alignment while Ta 2 O 5 exhibited type I in band energy alignment studies conducted via X‐Ray Electron Spectroscopy studies. [ 204 ] Figure shows some of the Ga 2 O 3 heterojunctions based PDs as reported in literature along with the energy band diagrams depicting their band alignments and the flow of carriers under deep‐UV illumination.…”

Electronic structure modification in Fe-substituted β-Ga2O3 from resonant photoemission and soft x-ray absorption spectroscopies

“…Figure 1(a) clearly shows that all the samples have six peaks in the studied 2θ range of 10 • -100 • . The two highly intense and sharp peaks located at 41.53 • and 89.57 • , denoted as (0006)S and (00012)S, are the Bragg reflections from the (0006) to (00012) planes of the c-Al 2 O 3 substrate [26,27]. The other four relatively broader peaks are identified as Bragg reflections from the (−201), (−402), (−603), and (−804) parallel set of planes of the β-Ga 2 O 3 [26,27].…”

“…The two highly intense and sharp peaks located at 41.53 • and 89.57 • , denoted as (0006)S and (00012)S, are the Bragg reflections from the (0006) to (00012) planes of the c-Al 2 O 3 substrate [26,27]. The other four relatively broader peaks are identified as Bragg reflections from the (−201), (−402), (−603), and (−804) parallel set of planes of the β-Ga 2 O 3 [26,27]. With an increase of Fe composition, the peak positions shift towards the lower angle side in the 2θ/ω-scan profiles, which is clearly shown in figure 1(b).…”

Mist CVD-based growth of crystalline alpha chromium oxide (α-Cr2O3) on c-plane sapphire substrate with chromium acetylacetonate as a precursor

“…Chromium oxide (Cr2O3) is a p-type wide bandgap (3.2 eV) semiconductor material that finds application in gallium oxide power devices [1], [2]. Gallium oxide (Ga2O3) based power devices with the alpha phase of Ga2O3 (α-Ga2O3) are grown on sapphire substrates with mist CVD [3]- [6].…”