| 摘要 |
The invention relates to a method and an arrangement for measuring the recombination lifetime of minority carriers in semiconductors. According to the method the semiconductor is illuminated by pulses of a light source, and the time dependence of the change in the microwave reflection caused by minority carriers generated in the semiconductor by light is detected so that the microwave guide is directly contacted with the semiconductor. Thus microwave reflection occurs from a significantly smaller part of the volume as compared to contact-free methods. The arrangement comprises a microwave generator (2) tunable by a varactor (1), the output of the generator (2) is connected to the input of an isolator (3), the output of which is connected to the first gate of a circulator (4), the second gate of which is connected to a contact needle (5) also through a coaxial cable, whereas the third gate of the circulator (4) is led to a detector (8) through a coaxial connection. The contact needle (5) carries the microwave field in direct contact to the semiconductor (6), which is the impedance closing the microwave path. The semiconductor (6) is optical excited from a laser light source (7), which is connected to one of the outputs of a pulse generator (12), the input of which is connected to the output of a central signal processing unit (13). To the same output, the inputs of the varactor (1) and the laser light source (7) are connected. The detector (8) is connected to the input of a sample and hold circuit (10) via an amplifier (9), which separates the low-frequency noise. The output of the sample and hold circuit (10) is fed back to the input of the amplifier (9). The output of the amplifier (9) is connected to a known transient recorder (11). The control and timing input of transient recorder (11) is connected to the output of pulse generator (12). To this output is connected the timing input of sample and hold circuit (10), as well. Signal processing is performed by the central signal processing unit (13), which also controls varactor (1), laser light source (7) and pulse generator (12).
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