Mukherjee Shagorika, Sitaram Sai Rahul, Yu Mingyu, Wang Xi, Law Stephanie
Department of Materials Science and Engineering, University of Delaware, 201 Dupont Hall, 127 The Green, Newark, DE, 19716, USA.
Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16802, USA.
Small Methods. 2025 Aug;9(8):e2500361. doi: 10.1002/smtd.202500361. Epub 2025 May 3.
Infrared (IR) gradient permittivity materials are the potential building blocks of miniature IR-devices such as an on-chip spectrometer. The manufacture of materials with permittivities that vary in the horizontal plane is demonstrated using shadow mask molecular beam epitaxy in Si:InAs films. However, to be useful, the permittivity gradient needs to be of high crystalline quality and its properties need to be tunable. In this paper, it is shown that it can control the permittivity gradient length and steepness by varying the shadow mask thickness. Samples grown with similar growth parameters and with 200 and 500 µm mask thicknesses show permittivity gradient widths of 18 and 39 µm on the flat mesa on one side and 11 and 23 µm on the film slope on the other side, respectively. The gradient steepnesses are 23.3 and 11.3 cm/µm on the flat mesa and 21.8 and 9.1 cm/µm on the film slope, for samples made with the 200 and 500 µm masks, respectively. This work clearly shows the ability to control the in-plane permittivity gradient in Si:InAs films, setting the stage for the creation of miniature IR devices.
红外（IR）梯度介电常数材料是诸如片上光谱仪等微型红外设备的潜在构建材料。利用阴影掩膜分子束外延技术在硅基铟砷（Si:InAs）薄膜中展示了制造介电常数在水平面上变化的材料。然而，要使其有用，介电常数梯度需要具有高结晶质量且其特性需要可调。在本文中，表明可以通过改变阴影掩膜厚度来控制介电常数梯度的长度和陡度。以相似生长参数生长且掩膜厚度分别为200和500微米的样品，在一侧的平坦台面处介电常数梯度宽度分别为18和39微米，在另一侧的薄膜斜坡处分别为11和23微米。对于使用200微米和500微米掩膜制成的样品，在平坦台面上的梯度陡度分别为23.3和11.3厘米/微米，在薄膜斜坡上分别为21.8和9.1厘米/微米。这项工作清楚地展示了控制硅基铟砷薄膜中面内介电常数梯度的能力，为制造微型红外设备奠定了基础。
