JFET optical detectors in the charge storage mode

The operation of a JFET as an optical detector in the charge storage mode is described and it is shown that due to the nondestructive readout, this device is particularly useful when high charge gains are required. On silicon, for example, it is calculated that small device structures should give charge gains > 10⁶. A method of resetting devices using the punchthrough effect is shown to reduce gain variations across an array and this principle is extended to a double punchthrough structure with a buried gate which can be read selectively. Measurements on lateral and longitudinal JFET structures verify these features and it is shown that they may be operated as two-terminal devices, a large voltage pulse being applied to the drain to reset and a small voltage to read.