Reinventing a p-type doping process for stable ZnO light emitting devices

A tough challenge for zinc oxide (ZnO) as the ultraviolet optoelectronics materials is realizing the stable and reliable ptype conductivity. Selfcompensation, coming from native donor-type point defects, is a big obstacle. In this work, we introduce a dynamic N doping process with molecular beam epitaxy, which is accomplished by a Zn, N-shutter periodic switch (a certain time shift between them for independent optimization of surface conditions). During the epitaxy, N adatoms are incorporated under the condition of (2 x 2) + Zn vacancies reconstruction on a Zn-polar surface, at which oxygen vacancies (V-O), the dominating compensating donors, are suppressed. With the p-ZnO with sufficient holes surviving, N concentration similar to 1 x 10(19) cm(-3), is employed in a p-i-n light emitting devices. Significant ultraviolet emission of electroluminescence spectra without broad green band (related to V-O) at room-temperature are demonstrated. The devices work incessantly without intentional cooling for over 300 h at a luminous intensity reduction of one order of magnitude under the driving of a 10 mA continuous current, which are the demonstration for p-ZnO stability and reliability.