Hydrogen-induced changes in the breakdown voltage of InP HEMTs

In this work, electrical measurements show that the breakdown voltage, BV_DG, of InP HEMTs increases following exposure to H₂. This BV_DG shift is nonrecoverable. The increase in BV_DG is found to be due to a decrease in the carrier concentration in the extrinsic portion of the device. We provide evidence that H₂ reacts with the exposed InAlAs surface in the extrinsic region next to the gate, changing the underlying carrier concentration. Hall measurements of capped and uncapped HEMT samples show that the decrease in sheet carrier concentration can be attributed to a modification of the exposed InAlAs surface. Consistent with this, XPS experiments on uncapped heterostructures give evidence of As loss from the InAlAs surface upon exposure to hydrogen.