Studies on DC transport and terahertz conductivity of granular molybdenum thin films for microwave radiation detector applications

TL;DR

This study investigates the electrical and optical properties of granular molybdenum thin films, revealing their potential for highly sensitive microwave and terahertz radiation detectors due to their unique superconducting and normal state characteristics.

Contribution

It provides new insights into the transport and terahertz optical properties of granular molybdenum films, highlighting their high superconducting transition temperatures and suitability for radiation detection.

Findings

Films have higher superconducting transition temperatures than bulk molybdenum.

Resistivity is in the >100 micro-Ohm-cm range, ideal for sensitive detectors.

Normal state is disordered bad metal with promising superconducting properties.

Abstract

The morphological, transport and terahertz optical properties of DC magnetron sputtered granular molybdenum thin-films with nano-grains embedded in an amorphous matrix have been studied in the normal and superconducting states. The superconducting transition temperatures of these films are much higher than that of bulk molybdenum. The optical properties of these thin-films have been studied using terahertz time-domain spectroscopy. Their properties have been compared with the existing materials used for the development of radiation detectors. The resistivity of the films lies in >100 micro-Ohm-cm range which is ideal for making highly sensitive radiation detectors. The Hall measurements indicate the presence of holes as the dominant carriers with very small mean free path and mobility. In the normal state, the films are disordered bad metal but they have large superfluid density and stiffness in their superconducting state. The normal state and superconducting properties of the films are very promising for their use in cryogenic radiation detectors for microwave, terahertz, and far IR frequency ranges.