Transient radiation and dose-enhancement effects in transistors

The response of bipolar transistors to ionizing radiation is considered for a relatively soft X-ray spectrum. A plasma focus device was used to irradiate several silicon transistors under controlled conditions so that the relative contributions to the radiation response could be isolated. The photocurrent response resulting from direct photon interaction with the silicon chip was in agreement with computations made on the basis of device geometry; however, contributions from packing effects were less predictable. The high Z package resulted in a nonuniform dose deposition in the device. The resultant dose enhancement is compared with integrated depth-dose profiles calculated with a Monte Carlo electron transport code.