Enhancement of InGaN-based MQW Grown on Si(111) Substrate by Underlying AlGaN/GaN SLS Cladding Layer
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1167-O02-05
Enhancement of InGaN-based MQW Grown on Si(111) Substrate by Underlying AlGaN/GaN SLS Cladding Layer Bin Abu Bakar Ahmad Shuhaimi1,2,*, Takaaki Suzue1,2, Yukiyasu Nomura1,2 , Yoshinori Maki1,2 and Takashi Egawa1,2 1 Research Center for Nano-Device and System, Nagoya Institute of Technology, Nagoya, Japan. 2 Graduate School of Engineering Physics, Electronics and Mechanics, Nagoya Institute of Technology, Nagoya, Japan.
ABSTRACT This paper reports enhanced internal-quantum-efficiency (IQE) in InGaN-based multiquantum-well (MQW) grown on Si(111) substrate with underlying strained-layer-superlattice (SLS) cladding layer for application in LDs and LEDs. In comparative study between a thick Al0.03Ga0.97N bulk and an Al0.06Ga0.94N/GaN SLS cladding layer, transmission-electronmicroscopy (TEM) images reveal that Al0.06Ga0.94N/GaN SLS cladding layer is effective to suppress threading dislocations. A higher IQE has been achieved in sample with underlying Al0.06Ga0.94N/GaN SLS cladding layer, compared to that of Al0.03Ga0.97N bulk cladding layer. IQE of 31.6% has been achieved in sample with underlying Al0.06Ga0.94N/GaN SLS cladding layer when the MQW thickness is reduced to 2 nm. INTRODUCTION GaN-based wide band-gap emitters grown on Si are very promising breakthrough for low-cost energy-saving applications. Silicon (Si) is a very promising substrate for GaN growth, which is low cost, widely available, having large surface diameter, and offering good current and thermal conductivity for device operation. However, a few issues that hindered epitaxial-growth of GaN on Si(111) substrate are cloudy and cracked epilayer, large wafer curvature and high threading dislocation density exceeding 1010 cm-2 in conventional metalorganic chemical vapor deposition (MOCVD) method. These are attributed by large lattice and thermal mismatch between GaN epilayer and Si(111) substrate of 17% and 116%, respectively. A thin AlN layer is generally used as seeding layer for GaN growth on Si substrate, followed by methods such as AlN/GaN or AlGaN/GaN multilayer [1-5], AlN interlayer [6-7], SixNy interlayer [8-9], etc, to offset tensile and thermal stress between GaN and Si, and to improve crystal quality in the subsequent epilayer. Despite the difficulties for GaN growth on Si, a few groups including ours have succeeded in growing good epitaxial quality GaN layer on Si(111) substrate with applications in LEDs [2-5] and HEMTs [10]. In this paper, we report an efficient suppression of threading dislocations in InGaN-based MQW sample grown on Si(111) substrate by an underlying Al0.06Ga0.94N/GaN strained-layer-superlattice (SLS) cladding layer, and an improvement of MQW internal-quantum-efficiency (IQE) by optimizing MQW thickness in sample with underlying Al0.06Ga0.94N/GaN SLS cladding layer. This work is intended for applications in GaN-based LDs and LEDs on Si substrate. ________________________________________ *
Corresponding author, e-mail: [email protected]
EXPERIMENT Samples in this study were grown on 2 inch Si(111) substrate by h
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