This paper gives a new explanation of the low-field noise emission from InSb. Theoretical predictions and experimental measurements with a fine tungsten probe (10-µm definition) show that there are very large fields at one corner of the cathode contact in the presence of a transverse magnetic field. Our experiments show that avalanching occurs near this point and the noise amplitude has a strong maximum there. In a longitudinal magnetic field all samples measured have shown inhomogeneities near the cathode contact, which are the source of noise.
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