Endurance Improvement of GaN Bipolar Charge Trapping Memory With Back Gate Injection

A GaN-based tunnel-oxide-free non-volatile memory device with fast program/erase (P/E) speed and a long retention time has been recently reported, but the high voltage for program still leads to a high electric field in the blocking oxide and thus limits the endurance. In this letter, we propose to improve the endurance by a less destructive program scheme based on back gate injection (BGI) and a reduced doping concentration of the p-channel. In the BGI process, holes in the p-channel can screen the electric field and thus alleviate the electrical stress to the blocking oxide, whereas the lower doping concentration can prolong the lifetime of the injected electrons from the back gate. As such, the memory is able to endure over 1010 P/E cycles and a -10-V/200-ns pulse is adequate for program, with an uncompromised long retention time.