InGaN-based light-emitting diodes with thyristor characteristic

Abstract We propose and demonstrate the InGaN-based light-emitting diodes (LEDs) with thyristor function for the first time by incorporating an Mg-doped p -GaN layer between the n -GaN layer and InGaN/GaN multiple-quantum-well active layer. Utilizing the thyristor-like structure, a distinctive negative differential resistance (NDR) appears on the I–V characteristics of InGaN-based LEDs. This unique bi-switching characteristics of the thyristor will enable a fast switching of the LEDs and thus reducing the complexity of the driving circuit design, making it a potential switching devices in the field of optical communications. In this work, the Mg doping concentration and thickness of the additionally added p -GaN layer were found to have a significant impact on the NDR. The formation of NDR becomes more and more obvious with the increase of Mg doping and thickness. In our structure, the Mg doping flow rate of about 0.583–1.057 μ mol min −1 and the thickness of about 300–400 nm yield the best NDR properties. The brightness of LEDs decreases monotonically with the increasing Mg doping flow rate. Moreover, when the Mg doping concentration is insufficient, two NDR regions will appear in the I–V characteristics as the thickness increases. When the thickness is set to 300 nm and the Mg doping flow rates are 0.583, 0.802, and 1.057 μ mol min −1 , the optical output powers of the LEDs are measured to be 13.1, 12.8, and 14.3 mW at the driving current of 201 mA while the output powers at 4.61 mA are 0.46, 0.52, and 0.54 mW. The forward voltages at 201 mA are 3.71, 3.75, and 3.95 V for the Mg doping flow rates of 0.583, 0.802, and 1.057 μ mol min −1 , respectively. The characteristics of the thyristor-like InGaN LEDs need to be further optimized to reduce the operating current.