Photo-injection studies of buried oxide layers in SIMOX and BESOI structures

Illumination of a BESOI sample with photon energy below 6 eV (no electron-hole pair generation on the oxide) under positive bias on the metal electrode results in positive charge in the oxide which can be almost completely eliminated by changing the bias polarity. The C-V curves exhibit large hysteresis effects after illumination. It is suggested that the mechanism is photolysis of Si-OH and/or Si-H groups which does not require electron injection: the resulting H+ ions then drift under bias. The behavior of the BESOI sample is different from both SIMOX BOX and thermal oxide, but is somewhat similar to that shown by deposited Si0₂ films