Band alignments of sputtered dielectrics on GaN

Abstract

The band alignments of sputtered ZrO2, Al2O3 and MgO on GaN have been measured experimentally using x-ray photoelectron spectroscopy (XPS). The valence band offsets (±0.2 eV) for ZrO2, Al2O3 and MgO on GaN using Kraut’s method and charge-corrected XPS core levels were found to be 0.4 eV, 1.1 eV and 1.2 eV with corresponding conduction band offsets (±0.2 eV) of 1.3 eV, 2.0 eV and 2.8 eV, respectively. The electrical characterization of metal insulator semiconductor (MIS)-capacitors with different gate dielectrics (ZrO2, Al2O3 and MgO) has been performed as well. The current density of the MIS-capacitors with gate dielectrics MgO and Al2O3 at a positive bias of 1 V show lower leakage currents of 3.2 × 10−6 A cm−2 and 5.3 × 10−6 A cm−2 respectively, whereas, the MIS-capacitors with ZrO2 gate dielectric have the highest leakage current of 6.2 × 10−4 A cm−2 at 1 V.

Band Line-up Investigation of Atomic Layer Deposited TiAlO and GaAlO on GaN

“…The VBO for Al2O3 of 1.13 ± 0.25 eV is in excellent agreement with the recent theoretical (1.17 eV) [39] and experimental (1.07 eV) studies (see Ref. 48 and references therein). As can be seen from Table I, the VBO decreases from 0.84 eV for 9% Ti to 0.61 eV for 36% Ti mixed oxide.…”

“…Therefore, in this work we have used Ga 2p 3/2 and Ti 2p 3/2 CLs. Furthermore, the δ SUB for GaN has been measured to be 17.05 eV, 13 being much smaller than widely cited literature values of 17.7-17.8 eV; 48 if the latter value for δ SUB is used in the Kraut method, the VBO is 0.55 ± 0.25 eV 13 and is in line with the measured value in this work within the accuracy of the method. It has also been reported recently that VBO for TiO 2 /AlGaN is 0.56 eV and for Al 2 O 3 /AlGaN is 1.00 eV by XPS and the Kraut method; 14 from these values, the VBO of 1.56 eV for TiO 2 /Al 2 O 3 interface can be deduced which correlates with 0.74 eV from this study calculated from measured VBOs for TiO 2 /GaN (0.39 eV) and Al 2 O 3 /GaN (1.13 eV) (see Table I).…”

“…Only for interfacial TiO 2 /GaN sample, there was an additional component in the Ti 2p CL fitting at 557.33 eV (not shown), which was attributed to Ti 2 O 3 in line with the previous XPS studies. 47 This interfacial layer and a possible existence of Ga-O bonds at the interface could be a source of positive charges on the GaN surface, 48 which is leading to accumulated surface and resulting in a small downward band bending for this sample.…”

ALD Growth of MgxCa1–xO on GaN and Its Band Offset Analysis

“…Band offset is mainly determined by the density of interfacial defects, which provides us a great method to investigate dielectric/semiconductor interfacial quality . The band offset of MgO on GaN was measured by several groups with XPS study. , In this work, we will apply Robertson’s metal-induced gap state (MIGS) theory to establish the quantitative relationship between the defect levels and the band alignment on different ratios of Mg x Ca 1– x O on GaN.…”

“…25 The band offset of MgO on GaN was measured by several groups with XPS study. 26,27 In this work, we will apply Robertson's metal-induced gap state (MIGS) theory 28 to establish the quantitative relationship between the defect levels and the band alignment on different ratios of Mg x Ca 1−x O on GaN.…”