Surface band bending and band alignment of plasma enhanced atomic layer deposited dielectrics on Ga- and N-face gallium nitride

Jialing Yang, Brianna S. Eller, Robert Nemanich

Research output: Contribution to journalArticle

32 Citations (Scopus)

Abstract

The effects of surface pretreatment, dielectric growth, and post deposition annealing on interface electronic structure and polarization charge compensation of Ga- and N-face bulk GaN were investigated. The cleaning process consisted of an ex-situ wet chemical NH4OH treatment and an in-situ elevated temperature NH3 plasma process to remove carbon contamination, reduce oxygen coverage, and potentially passivate N-vacancy related defects. After the cleaning process, carbon contamination decreased below the x-ray photoemission spectroscopy detection limit, and the oxygen coverage stabilized at ∼ 1 monolayer on both Ga- and N-face GaN. In addition, Ga- and N-face GaN had an upward band bending of 0.8±0.1eV and 0.6±0.1eV, respectively, which suggested the net charge of the surface states and polarization bound charge was similar on Ga- and N-face GaN. Furthermore, three dielectrics (HfO2, Al2O3, and SiO2) were prepared by plasma-enhanced atomic layer deposition on Ga- or N-face GaN and annealed in N2 ambient to investigate the effect of the polarization charge on the interface electronic structure and band offsets. The respective valence band offsets of HfO2, Al2O3, and SiO2 with respect to Ga- and N-face GaN were 1.4±0.1, 2.0±0.1, and 3.2±0.1eV, regardless of dielectric thickness. The corresponding conduction band offsets were 1.0±0.1, 1.3±0.1, and 2.3±0.1eV, respectively. Experimental band offset results were consistent with theoretical calculations based on the charge neutrality level model. The trend of band offsets for dielectric/GaN interfaces was related to the band gap and/or the electronic part of the dielectric constant. The effect of polarization charge on band offset was apparently screened by the dielectric-GaN interface states.

Original languageEnglish (US)
Article number123702
JournalJournal of Applied Physics
Volume116
Issue number12
DOIs
StatePublished - 2014

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gallium nitrides
alignment
polarization
cleaning
contamination
electronic structure
carbon
plasma temperature
oxygen
atomic layer epitaxy
pretreatment
conduction bands
photoelectric emission
permittivity
valence
trends
annealing
defects
electronics
spectroscopy

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

Surface band bending and band alignment of plasma enhanced atomic layer deposited dielectrics on Ga- and N-face gallium nitride. / Yang, Jialing; Eller, Brianna S.; Nemanich, Robert.

In: Journal of Applied Physics, Vol. 116, No. 12, 123702, 2014.

Research output: Contribution to journalArticle

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