Comparison of a Dominant Electron Trap in n-Type and p-Type GaNAs using Deep-Level Transient Spectroscopy

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Abstract

Both p -type and n -type dilute-nitrogen GaNAs epitaxial layers grown by metal-organic chemical vapor deposition were characterized by deep-level transient spectroscopy (DLTS). For each case, the dominant DLTS signal corresponds to an electron trap having an activation energy of about 0.2-0.3 eV for p -type GaNAs and about 0.3-0.4 eV for n -type GaNAs. In p -type GaNAs, the electron traps fill slowly, as the DLTS signal reaches saturation using zero-bias filling pulses with widths of 1 s. The electron traps fill quickly in the n -type GaNAs, as the DLTS signal does not typically increase after the shortest fill time of 10 μs. The electron-trap densities are calculated using modeling that accounts for the spatial region where traps fill and emit during DLTS measurement. A set of p -type samples with mid- 1016 cm-3 net acceptors has N content ranging from 0.02% to 1.2%, and the resulting electron-trap concentrations range from 1.4× 1017 to 4.3× 1017 cm-3. A set of n -type samples with mid- 1017 cm-3 doping has N content ranging from 0.011% to 0.45%, and the resulting electron-trap concentrations range from 7.6× 1014 to 3.6× 1016 cm-3. Additionally, a set of p -type samples with ∼0.25% N content has hole concentrations ranging from 4.3× 1016 to 1.3× 1017 cm-3, and the resulting electron-trap concentrations increase with acceptor doping ranging from 3.1× 1017 to 7.2× 1017 cm-3. A set of n -type samples with ∼0.25% N content has electron concentrations ranging from 4.5× 1016 to 7.8× 1017 cm-3. The resulting electron-trap concentrations also increase with donor concentration from 5.7× 1015 to 3.5× 1016 cm-3. The modeling of the Poole-Frenkel effect predicts that the trap may be about 100 meV deeper than implied by the measured activation energies.

Original languageAmerican English
Article number011604JVA
Pages (from-to)1252-1257
Number of pages6
JournalJournal of Vacuum Science and Technology A: Vacuum, Surfaces and Films
Volume24
Issue number4
DOIs
StatePublished - 2006

Bibliographical note

AVS 52nd International Symposium and Exhibit, October 30 - November 4, 2005, in Boston, Massachusetts.

NREL Publication Number

  • NREL/JA-520-38100

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