Atomic surface structure of MOVPE-prepared GaP(111)B

• Published in: Applied surface science Vol. 534; p. 147346
• Main Authors: Kleinschmidt, P., Mutombo, P., Berthold, T., Paszuk, A., Steidl, M., Ecke, G., Nägelein, A., Koppka, C., Supplie, O., Krischok, S., Romanyuk, O., Himmerlich, M., Hannappel, T.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 30.12.2020
• Subjects: AES; DFT; Gallium phosphide; MOVPE-preparation; STM; XPS; MOVPE-preparation; XPS; DFT; Gallium phosphide; STM; AES
• ISSN: 0169-4332
• DOI: 10.1016/j.apsusc.2020.147346

[Display omitted] •MOVPE preparation of GaP(111)B (phosphorus face).•Combination of STM, XPS, AES and AFM measurements with DFT calculations.•Atomic surface structure of GaP(111)B revealed.•Dangling bonds of partially hydrogen-terminated phosphorus face imaged. Controlling the surface formation of the group-V face of (111)-oriented III-V semiconductors is crucial for subsequent successful growth of III-V nanowires for electronic and optoelectronic applications. With a view to preparing GaP/Si(111) virtual substrates, we investigate the atomic structure of the MOVPE (metalorganic vapor phase epitaxy)-prepared GaP(111)B surface (phosphorus face). We find that upon high-temperature annealing in the H2-based MOVPE process ambience, the surface is phosphorus-depleted, as evidenced by X-ray photoemission spectroscopy (XPS). However, a combination of density functional theory calculations and scanning tunneling microscopy (STM) suggests the formation of a partially H-terminated phosphorus surface, where the STM contrast is due to electrons tunneling from non-terminated dangling bonds of the phosphorus face. Atomic force microscopy (AFM) reveals that a high proportion of the surface is covered by islands, which are confirmed as Ga-rich by Auger electron spectroscopy (AES). We conclude that the STM images of the samples after high-temperature annealing only reflect the flat regions of the partially H-terminated phosphorus face, whereas an increasing coverage with Ga-rich islands, as detected by AFM and AES, forms upon annealing and underlies the higher proportion of Ga in the XPS measurements.