Density Modulated Vertical Carbon Nanotube Architectures with Bolometric Effect

Abstract

Novel density-modulated carbon nanotube (CNT) blocks with controlled and tunable CNT densities in adjacent layers have been developed. Regions with varying densities are laterally patterned into different shapes with submicron resolution, enhancing the fabrication flexibility of new 3D nanoelectromechanical systems for diverse sensing applications. This technology platform adjusts lateral electrical resistance, mechanical properties such as effective Young's modulus, and both lateral and vertical thermal conductivity, which can vary by several orders of magnitude. Highlighting its potential, the CNTs exhibit broadband blackbody absorption from ultraviolet (UV) to terahertz (THz). The initial bolometric detector demonstrates features such as a voltage responsivity ${\Re }_v$ = 20.5 V W⁻¹, a response time of less than 0.1 ms, measured robust operation up to 200 °C, with fabricated device dimensions of 20 × 30 μm², and a low-cost design suitable for mass production. Further optimizations of the lateral design can reduce the device dimensions to as small as 5 × 5 μm² and improve the absorption in the main resistance region. Thus, this architecture provides a platform technology to increase the responsivity of the fabricated new 3D-based bolometer devices by several orders of magnitude. Tiny objects such as biological cells can be characterized in real time.