Title :
Correlation between forward voltage drop and local carrier lifetime for a large area segmented thyristor
Author :
Linnros, Jan ; Revsater, Roland ; Heijkenskjold, L. ; Norlin, Peter
Author_Institution :
Dept. of Electron., R. Inst. of Technol., Stockholm, Sweden
fDate :
6/1/1995 12:00:00 AM
Abstract :
The forward voltage drop for individual segments of a large area thyristor has been correlated to the local, bulk carrier lifetime by lifetime mapping of the the wafer after final device processing. The lifetime mapping was performed under high injection conditions using an all-optical technique where carriers were generated by a short YAG laser pulse and the subsequent carrier decay was monitored by an IR laser beam using free carrier absorption. The lateral resolution was ~100 μm. The lifetime map revealed heavily contaminated areas where the lifetime was reduced by more than an order of magnitude. The forward voltage drop for corresponding thyristor segments was high and, for some areas, no stable turn-on could be achieved. Deep Level Transient Spectroscopy characterization of contaminated areas confirmed the lifetime measurement results and suggest that the contamination is most likely due to metal impurities introduced in the first extended-time/high-temperature drive-in of the p-base. Device simulations showed qualitative agreement between the bulk carrier lifetime and the corresponding voltage drop
Keywords :
carrier lifetime; deep level transient spectroscopy; measurement by laser beam; thyristors; IR laser beam; all-optical technique; carrier decay; deep level transient spectroscopy characterization; final device processing; forward voltage drop; free carrier absorption; heavily contaminated areas; high injection conditions; large area segmented thyristor; lateral resolution; lifetime mapping; local carrier lifetime; metal impurities; short YAG laser pulse; Charge carrier lifetime; Condition monitoring; Contamination; Electromagnetic wave absorption; Laser beams; Lifetime estimation; Optical pulse generation; Spectroscopy; Thyristors; Voltage;
Journal_Title :
Electron Devices, IEEE Transactions on