High mobility ultrathin ZnO p-n homojunction modulated by Zn0.85Mg0.15O quantum barriers

摘要

The adding of ZnMgO asymmetric double barriers (ADB) in p-ZnO:(Li,N)-ZnO homojunction affects the p-n junction device performance prominently.Two different homojunctions are fabricated on Si (100) substrates by pulsed laser deposition;one is the traditional p-ZnO:(Li,N)-ZnO homojunction with different thicknesses named as S1 (250 nm) and S2 (500 nm),the other is the one with ADB embedded in the n-layer named as Q (265 nm).From the photoluminescence spectra,defect luminescence present in the S-series devices is effectively limited in the Q device.The current-voltage curve of the Q device shows Zener-diode rectification property because the two-dimensional electron gas tunnels through the narrow ZnMgO barrier under a reverse bias,thus decreasing the working p-n homojunction thickness from 500 nm to 265 nm.The ADB-modified homojunction shows higher carrier mobility in the Q device.The electroluminescence of the ZnO homojunction is improved in Q compared to S2,because the holes in p-type ZnO (Li,N) can cross the wide ZnMgO barrier under a forward bias voltage into the ZnO quantum well.Therefore,electron-hole recombination occurs in the narrow bandgap of n-type ZnO,creating an ultraviolet light-emitting diode using the ZnO homojunction.