Photoconductive Switches: The Role of Spatial Effects in Carrier Dynamics

✍ Scribed by M. Koch; M. Bieler; G. Hein; K. Pierz; U. Siegner

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 104 KB
• Volume: 221
• Category: Article
• ISSN: 0370-1972
• DOI: 10.1002/1521-3951(200009)221:1<429::aid-pssb429>3.0.co;2-e

✦ Synopsis

We present first experiments that visualize the spatial pattern formed by optically excited carriers in a photoconductive switch. The luminescence emitted from an electrically biased GaAs/AlGaAs multiple quantum well is spatially resolved with a CCD camera after optical excitation with femtosecond laser pulses. Information about the spatial electron and hole distributions is extracted from the measured luminescence patterns using a simple analytical model. Our analysis demonstrates that the field-driven electron±hole dynamics substantially varies across the excitation spot. This result can be traced back to the density dependence of screening combined with the lateral variation of the carrier density. Our results prove the importance of spatial effects for the carrier dynamics in photoconductive switches and open up new avenues for further optimization of these devices as, e.g., THz emitters.