University of Illinois Urbana-Champaign

Spectroscopic characterization of dry etch-induced modification in III-V semiconductors and semiconductor heterostructures

Maslar, James Edgar

This item is only available for download by members of the University of Illinois community. Students, faculty, and staff at the U of I may log in with your NetID and password to view the item. If you are trying to access an Illinois-restricted dissertation or thesis, you can request a copy through your library's Inter-Library Loan office or purchase a copy directly from ProQuest.

Permalink

https://hdl.handle.net/2142/21245

Description

Title
Spectroscopic characterization of dry etch-induced modification in III-V semiconductors and semiconductor heterostructures
Author(s)
Maslar, James Edgar
Issue Date
1994
Doctoral Committee Chair(s)
Bohn, Paul W.
Department of Study
Chemistry
Discipline
Chemistry
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
  • Chemistry, Analytical
  • Physics, Condensed Matter
  • Engineering, Materials Science
Language
eng
Abstract
  • The effects of dry etching on the structural and electrical properties of III-V semiconductors and semiconductor heterostructures were studied using vibrational and electronic Raman spectroscopy and low and room temperature photoluminescence spectroscopy. The frequency, intensity, and lineshape of the dipole-allowed and dipole-forbidden longitudinal optic (LO) phonon as well as the dipole-forbidden transverse optic phonon were used to evaluate structural modification in doped and undoped material. The intensities and frequencies of the coupled LO phonon-plasmon modes relative to those of the unscreened LO phonon were used to probe changes in the surface space charge region and free carrier concentration. Photoluminescence peak energies, intensity, and lineshape were used to evaluate crystal quality and defect identity.
  • Structural modification was investigated in GaAs etched in SiCl$\sb4$, SiCl$\sb4$/SiF$\sb4$, and CH$\sb4$/H$\sb2$ plasmas and sputtered in an Ar plasma. SiCl$\sb4$ and SiCl$\sb4$/SiF$\sb4$ etches both produced significant structural modification. CH$\sb4$/H$\sb2$ plasmas produced less structural modification, however, a highly disordered surface layer was still created. Electrical modification by the methane-based plasmas was found to depend weakly on the self-bias voltage and was confined to within ca. 125 A of the surface.
  • The effects of reactive ion etching (RIE) in methane-based plasmas as well as sputtering in Ar and He plasmas on InP were investigated. In general, methane-based plasmas showed far less structural damage than sputtering. Samples sputtered in Ar plasmas exhibited the most structural modification, however, at larger bias voltages some structural modification was observed for methane-based etches (except CH$\sb4$/H$\sb2$ plasmas). Of the methane-based etches CH$\sb4$/H$\sb2$ and CH$\sb4$/H$\sb2$/Ar plasmas exhibited the least structural modification. Electrical modification was also seen to be more extensive with sputter etches than methane-based etches. Samples sputtered in He plasmas showed more electrical perturbations than samples sputtered in Ar plasmas. Methane-based etches did affect electrical properties of InP. No clear trends were observed, although, in general, CH$\sb4$/H$\sb2$ etches resulted in the largest depletion widths.
  • The effects of HBr RIE and Ar sputtering on InGaAs and InAlAs were investigated. Ar sputtering of InGaAs resulted in significant structural modification. HBr-etching lead to significantly less structural modification, although some disorder was created by these etches. Ar sputtering of InAlAs also resulted in structural modification, although to a lesser degree than observed for InGaAs. Ar sputtering results in the formation of a high-donor density surface region, which leads to the creation of an electron accumulation layer in the near-surface region. A decrease in carrier concentration was observed to ca. 230 A in HBr-etched $n\sp+$-InAlAs.
  • The presence and shifts of the coupled phonon-two-dimensional electron gas (2DEG) plasmon modes in InGaAs/InAlAs heterostructures were used to investigate the effects of HBr RIE on the 2DEG properties. Etch-induced 2DEG modification was greatly reduced when the InAlAs barrier thickness was increased from 75 A to 350 A. For the structures with the smallest barrier thicknesses the decrease in 2DEG concentration was more strongly dependent on increased etch times than increased self-bias voltage.
Type of Resource
text
Permalink
http://hdl.handle.net/2142/21245
Copyright and License Information
Copyright 1994 Maslar, James Edgar

Owning Collections

Graduate Dissertations and Theses at Illinois PRIMARY
Graduate Theses and Dissertations at Illinois
Dissertations and Theses - Chemistry