Search

Aluminium gallium nitride (AlGaN)‐based ultraviolet‐B light‐emitting diodes (UVB LEDs) are expected to offer smart size, wider choice of UVB light emission in the wavelengths range of 280 nm > λ > 320 nm, and low cost as well as low power consumption compared with other UV light sources including toxic mercury UV‐lamps. The hole‐tunneling from p‐AlGaN side of UVB LED into the multi‐quantum‐wells (MQWs) is strongly dependent on the thickness (TFB) and Al‐contents of undoped (ud)‐AlGaN final barrier (FB). Herein, the photoluminescence (PL) efficiency from MQWs of the UVB LED devices is investigated and compared with the electroluminescence (EL) spectra as a function of TFB. Subsequently, the dependence of PL efficiency, external quantum efficiency (EQE), and light output power on the TFB of UVB LEDs is attempted, using the same growth condition for all samples except variation in TFB. When TFB is set to 6–7 nm, improvements in the EQE and light output power, respectively, from 4.3% and 7 mW to the high values of 5.6% and 17 mW in emission band of 295–300 nm under continuous‐wave (cw) at room temperature (RT) are achieved. [ABSTRACT FROM AUTHOR]

We demonstrated efficient ultraviolet (UV) photoluminescence (PL) with the wavelength ranging from 230 to 280 nm from Al[sub x]Ga[sub 1-x]N(AlN)/Al[sub y]Ga[sub 1-y]N multiquantum wells (MQWs) grown on SiC by metalorganic vapor phase epitaxy. We systematically investigated the PL intensity of the AlGaN-based MQWs with wide-band-gap AlGaN barriers as functions of QW thickness and Al content of barriers. Single-peak, efficient PL emission was obtained at 282-234 nm at 77 K from Al[sub x]Ga[sub 1-x]N(AlN)/Al[sub y]Ga[sub 1-y]N 5-layer MQWs with approximately 1.5-nm-thick active layers by changing the Al content of the AlxGa[sub 1-x]N barriers from 53% to 100%. The efficiency of the deep-UV emission from AlGaN-based QWs was as high as that of blue emission from InGaN-based QWs at 77 K. [ABSTRACT FROM AUTHOR]