Growth and Fabrication of High External Quantum Efficiency AlGaN-Based Deep Ultraviolet Light-Emitting Diode Grown on Pattern Si Substrate

Binh Tinh Tran,Hideki Hirayama

doi:10.1038/s41598-017-11757-1

Abstract

Growing III-V semiconductor materials on Si substrates for opto-electronic applications is challenging because their high lattice mismatch and different thermal expansion coefficients cause the epitaxial layers to have low quality. Here we report the growth of a high-quality AlN template on a micro-circle-patterned Si substrate by using NH3 pulsed-flow multilayer AlN growth and epitaxial lateral overgrowth techniques. Then, we fabricated and characterized a deep-ultraviolet light-emitting diode (UV-LED) device using this AlN/patterned Si. By using standard lithography and inductively coupled plasma etching, the Si substrate was prepared with very high pattern density and was made deep enough to grow a thick AlN template with high crystal quality and very few threading dislocations, allowing for further re-growth of the deep UV-LED device. And by combining a transparent p-AlGaN contact layer, an electron blocking layer and using this high quality AlN template: a deep UV-LED device fabricated and showed a strong single sharp electroluminescence (EL) peak at 325 nm and achieved an external quantum efficiency (EQE) of about 0.03%, for a deep UV-LED grown on Si substrate.

Highlights

With transverse-magnetic polarization along the direction normal to the surface, leading to the low efficiency
To determine the coalescence thickness as well as the threading dislocation density of the AlN template grown on the micro-circle-patterned Si substrate (mPSiS), we first used a focused ion beam technique to cut the sample as shown in Fig. 2A According to the cross-sectional scanning electron microscopy (SEM) image, coalescence began at the end of the third AlN layer, and the fourth and fifth layers were completely coalesced without any voids inside
We have produced a 325-nm-wavelength AlGaN-based deep ultraviolet light-emitting diode (UV-LED), which was grown on a micro-circle-patterned Si substrate for the first time, with AlN template X-ray diffraction (XRD) full width at half-maximum (FWHM) rocking curves of 620 and 1141 arcsec for the (002) and (102) reflection planes, respectively

Summary

Introduction

With transverse-magnetic polarization along the direction normal to the surface, leading to the low efficiency. A third reason may be that the p-GaN typically used for the contact layer strongly absorbs the light emitted from the AlGaN MQWs, resulting in low light extraction from the surface[18,20,21]. For these reasons, there have been very few reports about the development of deep UV-LEDs on Si substrates with high quantum efficiency and wavelengths shorter than 350 nm, which requires high Al content. We report on the growth, fabrication, and characterization of a deep UV-LED on patterned Si substrate with an emission wavelength belongs to UVA. The AlN template was placed in another MOCVD reactor to regrow a deep UV-LED structure and fabricate a device with an emission wavelength of 325 nm and high EQE

Methods

Results

Conclusion