Electroluminescence enhancement of SiGe/Si multiple quantum wells through nanowall structures

Abstract

The enhancement of light extraction from Si(0.5)Ge(0.5)/Si multiple quantum wells (MQWs) with nanowall structures fabricated by electron cyclotron resonance (ECR) plasma etching is presented. It is shown that the ECR plasma treatment does not damage the crystalline quality. At a driving current of 5.5 × 10(6) A m(-2), the light output intensity of the MQWs with nanowall structures shows an enhancement of about 50% compared with that of the original MQWs. In addition to the enhanced light extraction, the improved optoelectronic properties are also attributed to the strain relaxation in nanowall structures.

Fabrication and Photoluminescence Study of Large-Area Ordered and Size-Controlled GeSi Multi-quantum-well Nanopillar Arrays

“…2d , for the as-grown MQW sample, the peaks at 230, 302, 417, and 437 cm −1 are assigned to Si(2TA) L , Si(2TA) X , Si-Ge phonon mode, and Si-Si phonon (local) modes, respectively. For the ICP-etched samples, both peaks of Ge(LO) and Si-Ge mode have a redshift compared to the as-grown MQW sample, which is mainly resulting from the compressive strain relaxation [ 13 ]. The Raman results prove that the crystalline quality of the ICP-etched samples was not damaged during the etching process.…”

“…At the same time, they also pointed out that the real mechanisms for the PL enhancement were still not clear. The Chen group fabricated a randomly positioned SiGe/Si multi-quantum-well (MQW) nanowall by using electron cyclotron resonance plasma etching on an as-grown SiGe/Si MQW, and the measured electroluminescence intensity of the SiGe/Si MQW nanowalls increased to about 1.5 times for the enhancement of emission light extraction [ 13 ]. Chen et al also observed PL emission enhancement in size-uncontrollable Si/Ge superlattice pyramidal nanodots, which were fabricated by chemical selective etching through a self-assembled Ge QD mask [ 14 ].…”

Uniform SiGe/Si quantum well nanorod and nanodot arrays fabricated using nanosphere lithography

“…Many techniques including laser- [40] and metal-assisted [41] chemical etching have been reported to fabricate ‘black silicon’ with an ultra-low reflectance. The surface nanoroughening process in this study could be an alternative approach applied to SiGe-based nanodevices and optoelectronics, such as metal-oxide-Si tunneling diodes [42], light-emitting diodes [25], and photodetectors operating in the telecommunication range [28]. In addition, the SiGe/Si MQW nanopits and nanorods with well-defined spatial periodicity fabricated in this study would also be potential materials applied to photonic crystals [1] and phototransistors [43].…”

“…Chen also fabricated pyramidal nanodots that possess Si/Ge SLs by chemical selective etching through a self-assembled Ge QD nanomask and found an obvious enhancement in PL emission [24]. In addition, an improvement of light extraction from SiGe/Si MQWs with nanowall structures fabricated by electron cyclotron resonance plasma etching through a random Al-masked pattern was also reported [25]. However, few studies reported the fabrication of periodic nanostructure arrays composed of SiGe/Si MQWs using NSL.…”