Performance enhancement of UV quantum well light emitting diode through structure optimization
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In this paper, an extensive study is carried out via theoretical simulation to determine the electrical and optical characteristics of AlGaN based multi-quantum well near-ultra violet light emitting diodes (MQW-UV-LED) for the emission wavelength of 353 nm. The structure and characteristics of epitaxial layers used in UV-LEDs play a significant role in the performance of the device. We have studied dependence of device output characteristics on its layer structure and optimized the structure properties to improve the performance of the device. During the optimization process, thickness of quantum well layers, thickness of barrier layers, composition of electron blocking layer (EBL) and composition of barrier layer have been changed to their optimal values. In order to calculate the wavefunction, carrier densities, and discrete energy levels within the quantum well, a 6 × 6 Kohn–Luttinger Hamiltonian has been solved. A final structure with optimized values has been proposed in the end. The optimal values for quantum well thickness and barrier thickness are found to be 3.5 nm and 6 nm respectively. Optimum values from aluminium concentration in EBL and barriers are found to be 40% and 22% respectively. The output characteristics of the final device have been simulated and results are demonstrated. The performance of final device for varying temperature have also been simulated and displayed. The results achieved n this work may be beneficial to the entire opto-electronics community.
KeywordsUV-LED Efficiency droop Phosphor-less LEDs EBL LED simulations GaN LED
Shameem Ahmad, M. A. Raushan and M. J. siddiqui are grateful to the UGC, Govt. of India, New Delhi, for providing support under the DSA-I grant. P. A. Alvi is thankful to DST, Government of India, New Delhi for providing support under CURIE programme to Banasthali Vidyapith.
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