InGaN-based blue LED grown on Si(111) substrate

Abstract

This paper reports fabrication and characterization of InGaN-based blue light-emitting diode (LED) grown on Si(111) substrate. The LED structure in this study was grown on 2-inch n-type Si(111) substrate by metal-organic vapor-phase epitaxy (MOVPE). A 20 nm n-AlN layer was initially grown on the Si(111) substrate as nucleation layer, followed by a stack of n-AlN/n-GaN multilayers with respective thickness of 5 and 20 nm to reduce penetration of threading dislocations into the next grown layers. Subsequently, LED device layers were grown on the n-AlN/n-GaN multilayers, with 200 nm of n-GaN contact layer, active layer with 15 pairs of 2 nm In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.16</sub> Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.84</sub> N wells and 10 nm In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.08</sub> Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.92</sub> N barriers, a 10 nm p-Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.08</sub> Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.92</sub> N electron-block layer, and a 50 nm p-GaN contact layer. The sample was fabricated into operational LED using standard device fabrication methods, with light-emission area of 500 × 500 μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> square. Dry-etching with BCl <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> gas was used to expose n-GaN layer outside of the emission area for n-type electrode pad. A Ni/Au metallization was used for p-type semi-transparent and contact electrode pad on the top p-GaN layer, and Ti/Al/Ni/Au metallization was used for n-type contact electrode pad on the exposed n-GaN layer. Additionally, AuSb/Au metallization was fabricated on the backside of n-type Si(111) substrate as n-type electrode. In current-voltage (I-V) characteristics, the minimum operating voltage at 20 mA of the device is 3.6 V, with series resistance of 29 Ohm. In electroluminescence (EL) measurement, the LED shows single emission peak at 465 nm at injected current density of 120 A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , with full-width at half-maximum (FWHM) of 35 nm. In conclusion, we have successfully fabricated blue LED on Si(111) substrate with superior characteristics.