High hole concentration of p-type InGaN epitaxial layers grown by MOCVD
2005; Elsevier BV; Volume: 498; Issue: 1-2 Linguagem: Inglês
10.1016/j.tsf.2005.07.084
ISSN1879-2731
AutoresPo‐Chang Chen, Chin-Hsiang Chen, Shoou‐Jinn Chang, Yan-Kuin Su, Ping-Chuan Chang, Bohr-Ran Huang,
Tópico(s)Metal and Thin Film Mechanics
ResumoAbstractThe electrical and optical properties of Mg-doped In x Ga 1 x N were investigated herein. With an In mole fraction increase, the RTcarrier concentration was increased exponentially. Compared to Mg-doped GaN layers, it was found that we could achieve a high(1.65 1910 cm 3 ) hole concentration from the p-type InGaN with an indium content of 0.23. InGaN/GaN MQW blue LEDs without andwith a 5-nm-thick p-type In 0.23 Ga 0.77 N contact layer were also successfully fabricated. We could reduce the 20 mA operation voltage from3.78 V to 3.37 V by introducing a 5-nm-thick In 0.23 Ga 0.77 N layer on top of the p-type GaN layer and improve the blue LED EL intensityand output power by employing such a p-In 0.23 Ga 0.77 N layer.D 2005 Elsevier B.V. All rights reserved. Keywords: InGaN; MOCVD; PL; Tunneling contact layer; LED; Hole concentration; Operating voltage 1. IntroductionRecently, tremendous progress has been achieved inGaN-based light emitting diodes (LEDs). This has resultedin a variety of applications such as traffic light, full colordisplay and lighting. In order to achieve high performancenitride-based LEDs, it is required to reduce p-type GaNcontact resistance. Conventional nitride-based LEDs use p-type GaN as the p-contact layer [1,2]. However, theoperation voltage of such LEDs is still high due to thelow Mg ionization percentage, which will result in a highlyresistive top p-type GaN layer and a large metal/p-type GaNcontact resistance. Recent investigations have indicated thatseveral methods have been utilized to obtain low metal/p-type GaN contact resistance such as growth of Mg-dopedAlGaN/GaN strained layer superlattice [3,4], the n
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