Oxidation of the GaAs semiconductor at the Al 2 O 3 /GaAs junction

• Published in: Physical chemistry chemical physics : PCCP Vol. 17; no. 10; pp. 7060 - 7066
• Main Authors: Tuominen, Marjukka, Yasir, Muhammad, Lång, Jouko, Dahl, Johnny, Kuzmin, Mikhail, Mäkelä, Jaakko, Punkkinen, Marko, Laukkanen, Pekka, Kokko, Kalevi, Schulte, Karina, Punkkinen, Risto, Korpijärvi, Ville-Markus, Polojärvi, Ville, Guina, Mircea
• Format: Journal Article
• Language: English
• Published: 2015
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/C4CP05972G

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 Al 2 O 3 /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 Al 2 O 3 , decreases band-gap defect density at the Al 2 O 3 /GaAs interface. Concomitantly, X-ray photoelectron spectroscopy (XPS) from these Al 2 O 3 /GaAs interfaces shows that the high oxidation state of Ga (Ga 2 O 3 type) decreases, and the corresponding In 2 O 3 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.