Effects of polarity and surface treatment on Ga- and N-polar bulk GaN

Michael Foussekis, Josephus D. Ferguson, Joy Dorene McNamara, Alison A. Baski, Michael A. Reshchikov

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

The effects of polarity and surface treatment on the morphological, electrical, and optical behaviors in bulk GaN have been investigated. Kelvin probe, atomic force microscopy (AFM), and photoluminescence (PL) techniques were utilized to examine a set of freestanding, bulk GaN samples, which were grown by halide vapor phase epitaxy. The Ga- and N-polar surfaces were treated with either a mechanical polish (MP) or chemical mechanical polish (CMP), which influences the morphology, surface photovoltage (SPV), and PL behaviors. Topography studies indicate that the CMP-treated, Ga-polar surface is the smoothest of the sample set, whereas the MP-treated, N-polar surface has the highest root mean square roughness. Local current-voltage spectra obtained with conducting AFM reveal a higher forward-bias, turn-on voltage for the N-polar versus Ga-polar surfaces. Using a Kelvin probe, intensity-dependent SPV measurements are performed on samples with CMP-treated, Ga- and N-polar surfaces, and provide band bending values of 0.83 and 0.70 eV, respectively. The restoration of the SPV from CMP-treated surfaces behaves as predicted by a thermionic model, whereas restoration from MP-treated surfaces has a faster rate than expected. This result is possibly due to enhanced electron conduction via hopping between defect states to the surface. The quantum efficiency of the PL from the CMP- and MP-treated surfaces at room temperature is ∼1 and 1 × 10-5, respectively, suggesting high quenching of the PL for MP-treated surfaces by near-surface defects. Therefore, AFM, PL, and SPV data indicate that the MP-treated surfaces have a significantly higher density of surface defects.

Original languageEnglish (US)
Article number051210
JournalJournal of Vacuum Science and Technology B:Nanotechnology and Microelectronics
Volume30
Issue number5
DOIs
StatePublished - Jan 1 2012

Fingerprint

Industrial Oils
surface treatment
Surface treatment
polarity
Photoluminescence
photovoltages
photoluminescence
Atomic force microscopy
Surface defects
atomic force microscopy
surface defects
Restoration
restoration
Vapor phase epitaxy
Surface measurement
Electric potential
thermionics
probes
Quantum efficiency
electric potential

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Instrumentation
  • Process Chemistry and Technology
  • Surfaces, Coatings and Films
  • Electrical and Electronic Engineering
  • Materials Chemistry

Cite this

Effects of polarity and surface treatment on Ga- and N-polar bulk GaN. / Foussekis, Michael; Ferguson, Josephus D.; McNamara, Joy Dorene; Baski, Alison A.; Reshchikov, Michael A.

In: Journal of Vacuum Science and Technology B:Nanotechnology and Microelectronics, Vol. 30, No. 5, 051210, 01.01.2012.

Research output: Contribution to journalArticle

Foussekis, Michael ; Ferguson, Josephus D. ; McNamara, Joy Dorene ; Baski, Alison A. ; Reshchikov, Michael A. / Effects of polarity and surface treatment on Ga- and N-polar bulk GaN. In: Journal of Vacuum Science and Technology B:Nanotechnology and Microelectronics. 2012 ; Vol. 30, No. 5.
@article{fac86b9595e8416b9a0f29a10ea2eadf,
title = "Effects of polarity and surface treatment on Ga- and N-polar bulk GaN",
abstract = "The effects of polarity and surface treatment on the morphological, electrical, and optical behaviors in bulk GaN have been investigated. Kelvin probe, atomic force microscopy (AFM), and photoluminescence (PL) techniques were utilized to examine a set of freestanding, bulk GaN samples, which were grown by halide vapor phase epitaxy. The Ga- and N-polar surfaces were treated with either a mechanical polish (MP) or chemical mechanical polish (CMP), which influences the morphology, surface photovoltage (SPV), and PL behaviors. Topography studies indicate that the CMP-treated, Ga-polar surface is the smoothest of the sample set, whereas the MP-treated, N-polar surface has the highest root mean square roughness. Local current-voltage spectra obtained with conducting AFM reveal a higher forward-bias, turn-on voltage for the N-polar versus Ga-polar surfaces. Using a Kelvin probe, intensity-dependent SPV measurements are performed on samples with CMP-treated, Ga- and N-polar surfaces, and provide band bending values of 0.83 and 0.70 eV, respectively. The restoration of the SPV from CMP-treated surfaces behaves as predicted by a thermionic model, whereas restoration from MP-treated surfaces has a faster rate than expected. This result is possibly due to enhanced electron conduction via hopping between defect states to the surface. The quantum efficiency of the PL from the CMP- and MP-treated surfaces at room temperature is ∼1 and 1 × 10-5, respectively, suggesting high quenching of the PL for MP-treated surfaces by near-surface defects. Therefore, AFM, PL, and SPV data indicate that the MP-treated surfaces have a significantly higher density of surface defects.",
author = "Michael Foussekis and Ferguson, {Josephus D.} and McNamara, {Joy Dorene} and Baski, {Alison A.} and Reshchikov, {Michael A.}",
year = "2012",
month = "1",
day = "1",
doi = "10.1116/1.4751276",
language = "English (US)",
volume = "30",
journal = "Journal of Vacuum Science and Technology B:Nanotechnology and Microelectronics",
issn = "2166-2746",
publisher = "AVS Science and Technology Society",
number = "5",

}

TY - JOUR

T1 - Effects of polarity and surface treatment on Ga- and N-polar bulk GaN

AU - Foussekis, Michael

AU - Ferguson, Josephus D.

AU - McNamara, Joy Dorene

AU - Baski, Alison A.

AU - Reshchikov, Michael A.

PY - 2012/1/1

Y1 - 2012/1/1

N2 - The effects of polarity and surface treatment on the morphological, electrical, and optical behaviors in bulk GaN have been investigated. Kelvin probe, atomic force microscopy (AFM), and photoluminescence (PL) techniques were utilized to examine a set of freestanding, bulk GaN samples, which were grown by halide vapor phase epitaxy. The Ga- and N-polar surfaces were treated with either a mechanical polish (MP) or chemical mechanical polish (CMP), which influences the morphology, surface photovoltage (SPV), and PL behaviors. Topography studies indicate that the CMP-treated, Ga-polar surface is the smoothest of the sample set, whereas the MP-treated, N-polar surface has the highest root mean square roughness. Local current-voltage spectra obtained with conducting AFM reveal a higher forward-bias, turn-on voltage for the N-polar versus Ga-polar surfaces. Using a Kelvin probe, intensity-dependent SPV measurements are performed on samples with CMP-treated, Ga- and N-polar surfaces, and provide band bending values of 0.83 and 0.70 eV, respectively. The restoration of the SPV from CMP-treated surfaces behaves as predicted by a thermionic model, whereas restoration from MP-treated surfaces has a faster rate than expected. This result is possibly due to enhanced electron conduction via hopping between defect states to the surface. The quantum efficiency of the PL from the CMP- and MP-treated surfaces at room temperature is ∼1 and 1 × 10-5, respectively, suggesting high quenching of the PL for MP-treated surfaces by near-surface defects. Therefore, AFM, PL, and SPV data indicate that the MP-treated surfaces have a significantly higher density of surface defects.

AB - The effects of polarity and surface treatment on the morphological, electrical, and optical behaviors in bulk GaN have been investigated. Kelvin probe, atomic force microscopy (AFM), and photoluminescence (PL) techniques were utilized to examine a set of freestanding, bulk GaN samples, which were grown by halide vapor phase epitaxy. The Ga- and N-polar surfaces were treated with either a mechanical polish (MP) or chemical mechanical polish (CMP), which influences the morphology, surface photovoltage (SPV), and PL behaviors. Topography studies indicate that the CMP-treated, Ga-polar surface is the smoothest of the sample set, whereas the MP-treated, N-polar surface has the highest root mean square roughness. Local current-voltage spectra obtained with conducting AFM reveal a higher forward-bias, turn-on voltage for the N-polar versus Ga-polar surfaces. Using a Kelvin probe, intensity-dependent SPV measurements are performed on samples with CMP-treated, Ga- and N-polar surfaces, and provide band bending values of 0.83 and 0.70 eV, respectively. The restoration of the SPV from CMP-treated surfaces behaves as predicted by a thermionic model, whereas restoration from MP-treated surfaces has a faster rate than expected. This result is possibly due to enhanced electron conduction via hopping between defect states to the surface. The quantum efficiency of the PL from the CMP- and MP-treated surfaces at room temperature is ∼1 and 1 × 10-5, respectively, suggesting high quenching of the PL for MP-treated surfaces by near-surface defects. Therefore, AFM, PL, and SPV data indicate that the MP-treated surfaces have a significantly higher density of surface defects.

UR - http://www.scopus.com/inward/record.url?scp=84866489715&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84866489715&partnerID=8YFLogxK

U2 - 10.1116/1.4751276

DO - 10.1116/1.4751276

M3 - Article

AN - SCOPUS:84866489715

VL - 30

JO - Journal of Vacuum Science and Technology B:Nanotechnology and Microelectronics

JF - Journal of Vacuum Science and Technology B:Nanotechnology and Microelectronics

SN - 2166-2746

IS - 5

M1 - 051210

ER -