In addition, the SiGe/Si MQW nanorod arrays are also shown to exhibit excellent antireflective characteristics over a wide wavelength range. Methods Our initial samples consist of 50-period Si0.4Ge0.6/Si (3.6/6.4 nm nominally) MQWs capped with a 50-nm-thick Si layer, which were grown on (001) Si wafers using a multi-wafer ultra-high vacuum chemical vapor deposition (UHV/CVD) system. Pure SiH4 and GeH4 were used as gas precursors for Si or SiGe epitaxy. MGCD0103 price The formation procedure of SiGe/Si MQW nanorod arrays from the SiGe/Si MQW samples is illustrated in Figure 1(a): (1) assembly of the polystyrene

(PS) nanosphere monolayer arrays, (2) etching of the SiGe/Si MQW samples by RIE, and (3) removal of the nanosphere template. For the formation of SiGe/Si MQW nanodot arrays,

Pritelivir PS nanosphere arrays were first resized and then used as an etching mask, as shown in Figure 1(b). The following is a detailed introduction of the fabrication procedure. Figure 1 Schematic of the experimental procedure. To fabricate uniform SiGe/Si MQW (a) nanorod and (b) nanodot arrays from the Si0.4Ge0.6/Si MQWs using NSL combined with the RIE process. It is crucial to obtain a hydrophilic surface to allow the self-assembly of PS nanosphere monolayer arrays. In the first step, the as-grown SiGe/Si MQW samples were ultrasonically cleaned in acetone and in a solution of 4:1 H2SO4/H2O2 at 80°C for 30 min to prepare a hydrophilic surface. The SiGe/Si MQW samples were then coated with 800-nm-diameter PS nanospheres to form highly ordered and close-packed nanosphere arrays. Subsequently, a mixture of SF6 and O2 was

used to etch the samples at a working pressure of 25 mTorr for various durations to form the SiGe/Si MQW nanorod arrays. During the RIE etching, the inductively coupled plasma (ICP) power and bias of the etcher were kept at 50 W and 25 V, respectively. Finally, the PS nanosphere template was removed by ultrasonically cleaning in acetone solution. In addition, for the nanosphere resizing, O2 plasma RIE was used to shrink the PS Metalloexopeptidase nanospheres, allowing Ralimetinib chemical structure postspin feature size control. The surface morphologies of the etched samples were examined by scanning electron microscopy (SEM; FEI Quanta 200F, Hillsboro, OR, USA). Transmission electron microscopy (TEM) was carried out with a JEOL 2100 TEM (Akishima, Tokyo, Japan) operating at 200 kV to reveal detailed information about the microstructures of the etched nanostructures. PL measurements were performed at 10 K to study the optical properties of the SiGe/Si MQW nanorod and nanodot arrays using a 514.5-nm line of an Ar+ laser. The PL spectra were recorded by a liquid nitrogen-cooled Ge photodetector with the standard lock-in technique. We also measured total hemispherical reflectance spectra in air on a spectrophotometer with an integrating sphere (300 to 2,000 nm, Hitachi U-4100, Chiyoda, Tokyo, Japan) for the etched SiGe/Si MQW nanostructures.