AVS 52nd International Symposium
    Electronic Materials and Processing Thursday Sessions
       Session EM2-ThA

Paper EM2-ThA7
Comparison of a Dominant Electron Trap in n-Type and p-Type GaNAs Using Deep-Level Transient Spectroscopy

Thursday, November 3, 2005, 4:00 pm, Room 310

Session: Dilute Nitrides and Small Bandgap Semiconductors
Presenter: S.W. Johnston, National Renewable Energy Laboratory
Authors: S.W. Johnston, National Renewable Energy Laboratory
S.R. Kurtz, National Renewable Energy Laboratory
Correspondent: Click to Email
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 to 0.3 eV for p-type GaNAs and about 0.3 to 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 on the order of 1 to 10 seconds. When applying a large range of filling-pulse widths, the activation energy tends to decrease from about 0.3 eV for short filling pulses to about 0.2 eV for longer filling pulses. In n-type GaNAs, the electron trap activation energy also tends to slightly decrease with increasing filling-pulse widths. For short pulse widths of microseconds to milliseconds, the activation energy is just below 0.4 eV, and for long pulse widths of seconds, the activation energy is just above 0.3 eV. The electron traps fill quickly in the n-type GaNAs, as the DLTS signal approaches saturation in microseconds. The capture cross-sections determined by the DLTS Arrhenius plots are typically about 10@super -13@ to 10@super -12@ cm@super 2@. The electron-trap densities range from 10@super 15@ to 10@super 16@ cm@super -3@ in mid-10@super 17@ cm@super -3@ n-type-doped GaNAs having a bandgap of 1.35 to 1.4 eV. These trap parameters give an estimated carrier lifetime of 1 ns or substantially shorter.