Monolithic III-V on Metal for Thermal Metasurfaces

It has been proposed that metal-semiconductor-metal (MSM) structures can be used to tune the absorptivity of a metasurface at infrared wavelengths. Indium arsenide (InAs) is a low-band-gap, high-electron-mobility semiconductor that may enable rapid index tuning for dynamic control over the infrared spectrum. However, direct growth of III-V thin films on top of metals has typically resulted in small-grain, polycrystalline materials that are not amenable to high-quality devices. Previously, epitaxial wafers were used for this purpose. However, the epitaxial constraints required that InAs be used for both the tuning layer and the bottom "metallic" layer, limiting the range of accessible designs. In this work, we show a demonstration of direct growth of single-crystalline InAs on metal to build tunable absorbers/emitters in the infrared regime. The growth was carried out at a temperature of 300 °C by the low temperature templated liquid phase (LT-TLP) method. The size of InAs single-crystalline mesas is ∼2500 μm², enabling the desired device sizes. The proposed growth and device enable scalable and tunable infrared devices for various thermal-photonic applications.