Growth and optical properties of quaternary InAlGaN for 300 nm band UV-emitting devices

摘要

We demonstrated room temperature (RT) intense ultraviolet (UV) emission with wavelength in the range of 300-340 nm from In{sub}xAl{sub}yGa{sub}(1-x-y) quaternary alloys grown by metal organic vapor phase epitaxy (MOVPE). We found that the UV emission is considerably enhanced by In segregation upon introducing approximately 5% of In into AlGaN. We fabricated multi-quantum wells (MQWs) consisting of In{sub}(x1)Al{sub}(y1)Ga{sub}(1-x1-y1)N wells and In{sub}(x2)Al{sub}(y2)Ga{sub}(1-x2-y2)N barriers. The intensity of the 320 nm band emission from the InAlGaN-based MQWs was as strong as that of the 410 nm band emission from InGaN-based QWs at RT. We also fabricated an InAlGaN/InAlGaN single (S)QW and clearly observed In segregation of submicron size from cathodoluminescence (CL) images. The temperature dependence of photoluminescence (PL) emission for InAlGaN-based QWs was greatly improved in comparison with that of GaN- or AlGaN-based QWs. We also achieved a hole concentration of 3×10{sup}17 cm{sup}(-3) for large bandgap (around 4 eV) quaternary In{sub}(x)Al{sub}(y)Ga{sub}(1-x-y)N by Hall measurements. Finally, we fabricated UV light-emitting diodes (LEDs) using InAlGaN active region and achieved efficient 345 nm emission.