Investigation of Energy Band at Atomic-Layer-Deposited ZnO/β-Ga2O3 ( 2 ¯ 01 $$ \overline{2}01 $$ ) Heterojunctions

Abstract

The energy band alignment of ZnO/β-Ga2O3 () heterojunction was characterized by X-ray photoelectron spectroscopy (XPS). The ZnO films were grown by using atomic layer deposition at various temperatures. A type-I band alignment was identified for all the ZnO/β-Ga2O3 heterojunctions. The conduction (valence) band offset varied from 1.26 (0.20) eV to 1.47 (0.01) eV with the growth temperature increasing from 150 to 250 °C. The increased conduction band offset with temperature is mainly contributed by Zn interstitials in ZnO film. In the meanwhile, the acceptor-type complex defect Vzn + OH could account for the reduced valence band offset. These findings will facilitate the design and physical analysis of ZnO/β-Ga2O3 relevant electronic devices.

Oxides for Rectenna Technology

“…Figure 3a,b present electron affinities [9,17,[32][33][34][35][36][37][38][39][40][41][42][43][44] and band gap [33,35,36,38,43,[45][46][47][48][49][50][51][52][53][54][55] of typical oxides that have been used in the design and fabrication of MIM diodes. Full details are listed in Table 1 for completeness.…”

Band alignment and band bending at α-Ga2O3/ZnO n-n isotype hetero-interface

“…[7][8][9] Among the reported polymorphs, monoclinic Ga 2 O 3 (b-Ga 2 O 3 ) is the most investigated. Band alignment of b-Ga 2 O 3 with other semiconductors such as Si, 10 ZnO, 11 GaN, 12 SiC, 13 and AlN 14 has been investigated by x-ray photoemission spectroscopy (XPS).…”

“…18,19 X-ray photoemission spectroscopy is a powerful and commonly used technique to determine the band alignment at the interface of semiconductor heterostructures, wherein, most studies are usually focused on the determination of the valence band offset (VBO) and conduction band offset (CBO) without considering the band bending effect. [10][11][12][13][14] In fact, because surfaces and interfaces are invariably imperfect, lattice defects, dangling bonds, and interdiffusion across the interface are often present. 20 In addition to band alignment, band bending induced by charged interfacial states has been demonstrated to influence, and sometimes dominate carrier transport and device performance.…”

Toward controlling the Al2O3/ZnO interface properties by in situ ALD preparation

“…54 However, a temperature increase might also trigger the formation of oxygen vacancies especially in the ZnO film, resulting in an enhancement of Zn interstitials as reported in the recent literature. 55…”

“…62,63 Therefore, based on the literature and with respect to the position of the Fermi edge, for the following analysis we estimated a band gap value of ∼3.3 eV for our ZnO film. 64,65 This value is derived from a measurement of the valence band edge by UPS presented below. For a heavily n-type material the conduction band is within 50 to 100 meV of the conduction band minimum, as has been shown for Ga 2 O 3 .…”