Abstract
This study fabricates the optically active uniform SiGe/Si multiple quantum well (MQW) nanorod and nanodot arrays from the Si0.4Ge0.6/Si MQWs using nanosphere lithography (NSL) combined with the reactive ion etching (RIE) process. Compared to the as-grown sample, we observe an obvious blueshift in photoluminescence (PL) spectra for the SiGe/Si MQW nanorod and nanodot arrays, which can be attributed to the transition of PL emission from the upper multiple quantum dot-like SiGe layers to the lower MQWs. A possible mechanism associated with carrier localization is also proposed for the PL enhancement. In addition, the SiGe/Si MQW nanorod arrays are shown to exhibit excellent antireflective characteristics over a wide wavelength range. These results indicate that SiGe/Si MQW nanorod arrays fabricated using NSL combined with RIE would be potentially useful as an optoelectronic material operating in the telecommunication range.
Highlights
Over the past decades, there has been enormous interest in fabricating periodic semiconductor nanostructures, in which the semiconductor nanodot or nanorod array has shown its great potential for future applications in photonic crystals [1], nanoscale transistors [2], field electron emitters [3], biomaterials [4], and light-emitting devices [5]
We demonstrate the fabrication of optically active uniform SiGe/Si multiple quantum well (MQW) nanorod and nanodot arrays from the Si0.4Ge0.6/Si MQWs using Nanosphere lithography (NSL) combined with the reactive ion etching (RIE) process
Compared to the as-grown sample, we observe an obvious blueshift in PL spectra for the SiGe/Si MQW nanorod and nanodot arrays, which can be attributed to the transition of PL emission from the upper multiple quantum dot-like (MQD-like) SiGe layers to the lower MQWs
Summary
There has been enormous interest in fabricating periodic semiconductor nanostructures, in which the semiconductor nanodot or nanorod array has shown its great potential for future applications in photonic crystals [1], nanoscale transistors [2], field electron emitters [3], biomaterials [4], and light-emitting devices [5]. One important approach is the combination of Si with other semiconductor materials, such as Ge or Si1 − xGex alloys for heterostructures For this purpose, Si/Ge superlattices (SLs) [21], multiple quantum wells (MQWs) [22], and multiple quantum dots (MQDs) [23] have been demonstrated to adjust the bandgap and reduce nonradiative recombination. 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 reported [25]. Few studies reported the fabrication of periodic nanostructure arrays composed of SiGe/Si MQWs using NSL. We demonstrate the fabrication of optically active uniform SiGe/Si MQW nanorod and nanodot arrays from the Si0.4Ge0.6/Si MQWs using NSL combined with the reactive ion etching (RIE) process. The SiGe/Si MQW nanorod arrays are shown to exhibit excellent antireflective characteristics over a wide wavelength range
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