High mobility ultrathin ZnO p–n homojunction modulated by Zn_0.85Mg_0.15O quantum barriers

【摘要】 The adding of ZnMgO asymmetric double barriers（ADB） in p-ZnO:（Li, N）/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）/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 to265 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.更多还原

【Abstract】 The adding of ZnMgO asymmetric double barriers（ADB） in p-ZnO:（Li, N）/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）/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 to265 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.更多还原