Epitaxial growth of MgO/Ga₂O₃ heterostructure and its band alignment studied by X-ray photoemission spectroscopy

Abstract

We have grown an epitaxial MgO/Ga 2 O 3 heterostructure on a MgO(001) substrate by molecular beam epitaxy. Crystallographic studies revealed the out-of-plane and in-plane crystal orientations between the MgO overlayer and the Ga 2 O 3 layer, which were MgO(001) k β-Ga 2 O 3 (001) and MgO[100] k β-Ga 2 O 3 ½02 1, respectively. The valence band offset at the MgO/β-Ga 2 O 3 interface was determined to be 0.19 eV (type-II band alignment) by X-ray photoelectron spectroscopy, resulting in a large conduction band offset of 2.7-3.2 eV. These results indicate that MgO is a promising potential barrier for electrons in an epitaxial MgO/Ga 2 O 3 multilayered structure.

Band alignments of β-Ga2O3 with MgO, Al2O3 and MgAl2O4 measured by x-ray photoelectron spectroscopy

“…Compared to the results in [43], we have a type I band alignment (as given in figure 2(d)) instead of a type II band alignment (fail in holes confinement), which is possible due to the high growth temperatures of 1000 °C applied in the MBE technique. From the above information, we may indicate that the MgO dielectric could provide better confinement for both electrons and holes transport across the heterointerfaces between MgO and β-Ga 2 O 3 and have the potential to be employed in β-Ga 2 O 3 MOS devices to prevent reverse leakage current.…”

“…The bandgap ( E g ), dielectric constant (k), valence band offset (∆E V ), conduction band offset (∆E C ), and bandgap alignment types were listed in this table to be compared. As summarized in figure 4 corresponding to the data in table 1, the ∆E C of β-Ga 2 O 3 /MgO heterojunction is a little smaller than that in [43], but the ∆E V is positive other than the negative value suggesting an excellent hole confinement. In addition, the ∆E C obtained from β-Ga 2 O 3 /MgAl 2 O 4 heterojunction is competitive to AlN, LaAlO 4 , Al 2 O 3 , HfSiO 4 , and MgO, and even the ∆E V is superior to the others for confining the holes transports across the corresponding heterointerfaces.…”

X-Ray Photoemission Investigation of the Beryllium Oxide Band Alignment with Magnesium Oxide and Estimates for Other Insulating and Conducting Oxides

“…Thus, we can utilize our measurement for the BeO/MgO VBO and those for other interfaces with MgO to predict the band alignment between BeO and additional materials. We in particular take advantage of prior reports of the band alignment at MgO/ZnO (63,65), MgO/Ga 2 O 3 (73), MgO/InGaZnO 4 (66), MgO/NiO (74), and MgO/TiO 2 ( 60) interfaces (see Table II).…”

“…Utilizing the previously reported MgO/X VBO values summarized in Table II, we calculate the BeO VBO with ZnO, NiO, Ga 2 O 3 , InGaZnO 4 , and TiO 2 to be 1.15 ± 0.4, 2.4 ± 0.4, 0.3 ± 0.2, 0.9 ± 0.2, and 1.7 ± 0.2 eV, respectively. Utilizing the reported bandgaps for each oxide material (63)(64)(65)(66)(67)(68)(69)(70)(71)(72)(73)(74), we can additionally calculate the respective CBO for each interface. Both the calculated CBO and VBO values are summarized in Table III.…”

Heteroepitaxial β‐Ga2O3 on Conductive Ceramic Templates: Toward Ultrahigh Gain Deep‐Ultraviolet Photodetection

“…have also investigated the epitaxial growth of β‐Ga 2 O 3 directly on bulk MgO using molecular beam epitaxy (MBE) and studied the energy band alignment at the heterointerface, but their study lacks insight into the fact that bulk MgO surfaces are incomparable to those of epitaxially grown MgO dielectric layers; therefore, practical device demonstration based on their surface science study was impossible. [ 34 ] Similarly, Wang et al. investigated the epitaxial growth of β‐Ga 2 O 3 on bulk potassium tantalum oxide (KTaO 3 ) using metalorganic vapor‐phase epitaxy.…”