Electronic properties of light-induced recombination centers in boron-doped Czochralski silicon
Abstract
In order to study the electronic properties of the recombination centers responsible for the light-induced carrier lifetime degradation commonly observed in high-purity boron-doped Czochralski (Cz) silicon, injection-level dependent carrier lifetime measurements are performed on a large number of boron-doped p-type Cz silicon wafers of various resistivities (1-31 Ω cm) prior to and after light degradation. The measurement technique used is the contactless quasi-steady-state photoconductance method, allowing carrier lifetime measurements over a very broad injection range between 1012 and 1017cm-3. To eliminate all recombination channels not related to the degradation effect, the difference of the inverse lifetimes measured after and before light degradation is evaluated. A detailed analysis of the injection level dependence of the carrier lifetime change using the Shockley-Read-Hall theory shows that the fundamental recombination center created during illumination has an energy level between Ev+0.35 and Ec-0.45 eV and an electron/hole capture time constant ratio between 0.1 and 0.2. This deep-level center is observed in all samples and is attributed to a new type of boron-oxygen complex. Besides this fundamental defect, in some samples an additional shallow-level recombination center at 0.15 eV below Ec or above Ev is found to be activated during light exposure. This second center dominates the light-degraded carrier lifetime only under high-injection conditions and is hence only of minor importance for low-injection operated devices.
- Publication:
-
Journal of Applied Physics
- Pub Date:
- September 1999
- DOI:
- 10.1063/1.371186
- Bibcode:
- 1999JAP....86.3175S
- Keywords:
-
- 72.20.Jv;
- 72.40.+w;
- 71.55.Cn;
- 72.80.Cw;
- 73.50.Gr;
- 73.50.Pz;
- 73.61.Cw;
- Charge carriers: generation recombination lifetime and trapping;
- Photoconduction and photovoltaic effects;
- Elemental semiconductors;
- Elemental semiconductors;
- Charge carriers: generation recombination lifetime trapping mean free paths;
- Photoconduction and photovoltaic effects;
- Elemental semiconductors