Accession Number : ADA329784

Title :   A Study of Impact Ionization and Breakdown Phenomena in SiGe Devices.

Descriptive Note : Final rept. 30 Jun 94-29 Jun 97,

Corporate Author : MICHIGAN UNIV ANN ARBOR DEPT OF ELECTRICAL ENGINEERING

Personal Author(s) : Bhattacharya, P.

PDF Url : ADA329784

Report Date : 03 SEP 1997

Pagination or Media Count : 22

Abstract : The spectral response and impact ionization coefficient ration of Si(1-x)Ge(x) have been determined. Measurements were made on p+-i-n+ diodes grown by solid/gas source molecular beam epitaxy. The diodes are characterized by reverse breakdown voltages of 4-12V and dark currents of 20-170pA/micrometers 2. The long wavelength cut-off of the diodes increases from 1.2 micrometers to 1.6 micrometers as x increases from 0.08 to 1.0 with a maximum responsivity of 0.5 A/W in all the diodes tested. The ratio alpha/beta varies from 3.3 to 0.3 in the same composition range, with alpha/beta=1 at x congruent 0.45. These results have important implications in the use of this material system in various photodetection applications. As part of this project we also investigated the problem of high-level n-type doping of Si and SiGe, which is required for high quality diodes. The use of supersonically injected pulses of phosphine to achieve uniform and high levels of n-type doping in Si during gas-source molecular beam epitaxy was demonstrated. Uniform n-type doping up to levels of 5X10(exp 19) cu cm is obtained. SiGe/Si junction diodes made with this doping technique show good doping profiles and rectifying characteristics.

Descriptors :   *N TYPE SEMICONDUCTORS, *PHOTODIODES, *BREAKDOWN(ELECTRONIC THRESHOLD), REACTION TIME, PROFILOMETERS, SPECTRA, IONIZATION, PHOTODETECTION, DOPING, PIN DIODES, JUNCTION DIODES, WAVELENGTH DIVISION MULTIPLEXING.

Subject Categories : Solid State Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE