Identification of the dominant electron deep trap in a-Si:H: A critical test of the defect pool vs. defect relaxation pictures
Modulated photocurrent (MPC) measurements in intrinsic a-Si:H reveal a prominent band of electron deep traps with a thermal emission energy near 0.6 eV. The authors have identified this defect band by directly comparing MPC and ESR spectra for both an intrinsic and a lightly n-type doped sample for a various metastable states such that the Fermi level, E{sub F}, ranges from less than 0.5 eV to more than 0.7 eV below E{sub C}. This comparison unambiguously demonstrates that the MPC band arises from the D{sup 0} charge state of the defects (specifically, the D{sup {minus}}/D{sup 0} transition). This identification is also confirmed when the quasi-Fermi level is varied by the application of light bias even though the peak emission rate from the MPC defect band is changed by more than a factor of 100. These observations specifically rule out the possibility of large populations of charged defects in intrinsic samples predicted by proponents of the defect pool model. Instead, observed behaviors have a natural explanation in terms of a defect relaxation process.
- Research Organization:
- Univ. of Oregon, Eugene, OR (US)
- Sponsoring Organization:
- National Science Foundation
- OSTI ID:
- 20085482
- Country of Publication:
- United States
- Language:
- English
Similar Records
Band bending and oxygen-induced defects in a -Si:H
Recombination in a-Si:H: Results from the standard and defect pool models