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Control of defect densities at insulator/Ga xIn1− xAs interfaces is essential for optimal operation of various devices like transistors and infrared detectors to suppress, for example, nonradiative recombination, Fermi-level pinning, and leakage currents. It is reported that a thin InO x interface layer is useful to limit the formation of these defects by showing effect of InO x on quantum efficiency of Ga0.45In0.55As detector and on photoluminescence of GaAs. A study of the Al2O3/GaAs interface via hard X-ray synchrotron photoelectron spectroscopy reveals chemical structure changes at the interface induced by this beneficial InO x incorporation: the InO x sheet acts as an O diffusion barrier that prevents oxidation of GaAs and concomitant As bond rupture. [ABSTRACT FROM AUTHOR]

The article discusses research on the atomically abrupt interfaces of oxide/semiconductor junction (OSJ) that contain the prototypical silicon dioxide (SiO), film on indium gallium arsenide (GaInAs), gallium arsanide (GaAs), germanium (Ge) semiconductors through capacitance-voltage, photoluminescence and synchrotron-radiation photoelectron spectroscopy. The III-V semiconductor interaction with silicon was also investigated.

Atomic-scale understanding and processing of the oxidation of III–V compound–semiconductor surfaces are essential for developing materials for various devices (e.g., transistors, solar cells, and light emitting diodes). The oxidation-induced defect-rich phases at the interfaces of oxide/III–V junctions significantly affect the electrical performance of devices. In this study, a method to control the GaAs oxidation and interfacial defect density at the prototypical Al2O3/GaAs junction grown via atomic layer deposition (ALD) is demonstrated. Namely, pre-oxidation of GaAs(100) with an In-induced c(8 × 2) surface reconstruction, leading to a crystalline c(4 × 2)–O interface oxide before ALD of Al2O3, decreases band-gap defect density at the Al2O3/GaAs interface. Concomitantly, X-ray photoelectron spectroscopy (XPS) from these Al2O3/GaAs interfaces shows that the high oxidation state of Ga (Ga2O3 type) decreases, and the corresponding In2O3 type phase forms when employing the c(4 × 2)–O interface layer. Detailed synchrotron-radiation XPS of the counterpart c(4 × 2)–O oxide of InAs(100) has been utilized to elucidate the atomic structure of the useful c(4 × 2)–O interface layer and its oxidation process. The spectral analysis reveals that three different oxygen sites, five oxidation-induced group-III atomic sites with core-level shifts between −0.2 eV and +1.0 eV, and hardly any oxygen-induced changes at the As sites form during the oxidation. These results, discussed within the current atomic model of the c(4 × 2)–O interface, provide insight into the atomic structures of oxide/III–V interfaces and a way to control the semiconductor oxidation. [ABSTRACT FROM AUTHOR]

X-ray photoelectron spectroscopy (XPS) is one of the most used methods in a diverse field of materials science and engineering. The elemental core-level binding energies (BE) and core-level shifts (CLS) are determined and interpreted in the XPS. Oxidation is commonly considered to increase the BE of the core electrons of metal and semiconductor elements (i.e., positive BE shift due to O bonds), because valence electron charge density moves toward electronegative O atoms in the intuitive charge-transfer model. Here we demonstrate that this BE hypothesis is not generally valid by presenting XPS spectra and a consistent model of atomic processes occurring at HfO2/InP interface including negative In CLSs. It is shown theoretically for abrupt HfO2/InP model structures that there is no correlation between the In CLSs and the number of oxygen neighbors. However, the P CLSs can be estimated using the number of close O neighbors. First native oxide model interfaces for III-V semiconductors are introduced. The results obtained from ab initio calculations and synchrotron XPS measurements emphasize the importance of complementary analyses in various academic and industrial investigations where CLSs are at the heart of advancing knowledge. [ABSTRACT FROM AUTHOR]

Strong Fermi-level pinning (FLP) near the valence-band maximum on n-type Ge surfaces has been a long-standing challenge in semiconductor physics, and the nature of this phenomenon has been heavily debated for years. Here, we report a systematic synchrotron-based photoemission study of atomically well-defined Ge(100) surfaces and interfaces to elucidate the origin of FLP in such systems. It is experimentally shown that the FLP on n-Ge is not due to the dangling-bond, back-bond, and defect states, but is strongly contributed by the evanescent state of the Ge bulk. The conditions required for alleviating the FLP and even the implementation of a flatband structure on Ge(100) are formulated. Such a structure is realized in the BaO/Ge(100) system where one can obtain control over the Fermi-level position in the Ge gap. These findings are not only important from a fundamental viewpoint, but also open a route to producing Ohmic metal-insulator-semiconductor contacts for n-type Ge-based technology. [ABSTRACT FROM AUTHOR]

InAs crystals are emerging materials for various devices like radio frequency transistors and infrared sensors. Control of oxidation-induced changes is essential for decreasing amounts of the harmful InAs surface (or interface) defects because it is hard to avoid the energetically favored oxidation of InAs surface parts in device processing. We have characterized atomic-layer-deposition (ALD) grown Al 2 O 3 /InAs interfaces, preoxidized differently, with synchrotron hard X-ray photoelectron spectroscopy (HAXPES), low-energy electron diffraction, scanning tunneling microscopy, and time-of-flight elastic recoil detection analysis. The chemical environment and core-level shifts are clarified for well-embedded InAs interfaces (12 nm Al 2 O 3 ) to avoid, in particular, effects of a significant potential change at the vacuum-solid interface. High-resolution As 3d spectra reveal that the Al 2 O 3 /InAs interface, which was sputter-cleaned before ALD, includes +1.0 eV shift, whereas As 3d of the preoxidized (3 × 1)-O interface exhibits a shift of -0.51 eV. The measurements also indicate that an As 2 O 3 type structure is not crucial in controlling defect densities. Regarding In 4d measurements, the sputtered InAs interface includes only a +0.29 eV shift, while the In 4d shift around -0.3 eV is found to be inherent for the crystalline oxidized interfaces. Thus, the negative shifts, which have been usually associated with dangling bonds, are not necessarily an indication of such point defects as previously expected. In contrast, the negative shifts can arise from bonding with O atoms. Therefore, specific care should be directed in determining the bulk-component positions in photoelectron studies. Finally, we present an approach to transfer the InAs oxidation results to a device process of high electron mobility transistors (HEMT) using an As-rich III-V surface and In deposition. The approach is found to decrease a gate leakage current of HEMT without losing the gate controllability.