Blue-Green Light Emitting Diodes with New p-Contact Layers: ZnSe/BeTe

Abstract

We have fabricated ZnCdSe/ZnMgBeSe single quantum well (SQW) light emitting diode (LED) structures with ZnSe:N/BeTe:N p-contact layers. The electrical properties of this p-contact layer scheme were evaluated for the use in ZnSe-based II–VI LDs. The specific contact resistance for Au/p-ZnSe/p-BeTe ohmic contact layers, which was measured by the transmission line model (TLM) method, was as low as 4.2 × 10–4 Ωcm2 even without annealing when the ZnSe layer thickness is 5 nm. The composition of quaternary ZnMgBeSe was determined using a ZnBeSe/ZnMgBeSe layer structure by PL and X-ray measurements. The p-type doping property was investigated for ZnMgBeSe with different compositions, and Na–Nd drastically decreases with increasing band gap energy the same as that of the ZnMgSSe:N system. The fabricated LEDs show a strong electroluminescence under dc bias at room temperature.