J Comput Electron DOI 10.1007/s10825-016-0838-x Comparative performance analysis of InGaN/GaN multi-quantum-well light-emitting diodes with p- and n-type step-doped barriers Sumitra Singh 1,2 · Pranav Utpalla 1,2,3 · Suchandan Pal 1,2 · Chenna Dhanavantri 1,2 © Springer Science+Business Media New York 2016 Abstract The performance of InGaN/GaN light-emitting diodes (LEDs) with multiple-quantum-well barriers formed from alternating p- and undoped regions is compared with that of reference devices having similar epilayer struc- ture but with barriers formed from alternating n- and undoped regions. Simulations verify that p-type step-doping in the quantum barriers is more effective in reducing the polarization-induced electric field and lowering the energy barrier for hole transport as well as increasing the barrier height of the conduction band to confine electrons, thereby enhancing the radiative recombination rate compared with n-type step doping in the quantum barriers. This profile also increments hole injection and provides a more uni- form carrier distribution across the multiple quantum wells. According to the simulation results, when using the alter- nating stepwise doping profile in the barrier regions in the proposed structure, the internal quantum efficiency is remarkably improved, offering dual advantages of a homo- geneous hole distribution due to the undoped region and a reduced valence-band barrier height due to the p-doping. Keywords InGaN/GaN · Internal quantum efficiency (IQE) · Light-emitting diodes (LEDs) · Multiple quantum well (MQW) · Step-doped barrier B Sumitra Singh sumitra@ceeri.ernet.in 1 CSIR–Network of Institutes for Solar Energy (CSIR–NISE), Pilani, India 2 Opto-electronic Devices Group, CSIR–Central Electronics Engineering Research Institute (CSIR–CEERI), Pilani, Rajasthan 333 031, India 3 Birla Institute of Technology and Science – Pilani, Pilani Campus, Pilani, Rajasthan 333 031, India 1 Introduction InGaN/GaN light-emitting diodes (LEDs) have been inves- tigated over the last decade due to their promising and wide range of applications from general illumination to informa- tion displays, sensors, and communication, combined with their environmental friendliness compared with traditional incandescent bulbs. The LED efficiency is usually high at lower current density, but suffers from the major issue of efficiency droop at higher current density. Continuous efforts are being made to improve their efficiency, even at higher currents. There is as yet no consensus on a single cause of efficiency droop, but several models have been proposed to explain this effect, including Auger recombination [1], car- rier leakage [2–5], carrier overflow enhanced by the internal polarization field [5], junction heating [6], current crowding [7], and poor hole injection [8, 9]. Due to the higher mobility of electrons and the effect of polarization-induced electric fields, electrons are transported easily, leading to their inad- equate confinement in the active region. On the other hand, owing to their lower mobility, the distribution of holes is nonuniform across multiple quantum wells (MQWs), with most carriers accumulating in the quantum wells (QWs) close to the p-layer. This leads to poor overlap of the electron–hole wavefunctions, thus reducing the radiative recombination rate. Use of uniformly p-doped and undoped layers can substantially increase the radiative recombination rate [10], which is highly desirable for the development of high- efficiency LEDs. Radiative recombination is enhanced by greater spatial overlap between the electron–hole wavefunc- tions as well as increased carrier concentration (of electrons as well as holes). The spatial overlap of the electron–hole wavefunctions has been investigated, and a staggered con- figuration of InGaN quantum wells proposed [11–14]. For increased carrier concentration, better hole injection and effi- 123