Dielectric performance and cryogenic stability of CdPS3 for quantum device applications

Abstract

One of the critical challenges in advancing quantum computing is mitigating material defects, particularly at the interfaces of superconducting layers and circuits. High dielectric losses further limit performance, necessitating stable high-κ materials. In this work, we introduce Cadmium Trithiophosphate (CdPS₃) as a promising high-κ material at the nanoscale with a dielectric constant up to 10 at 44.07 nm thickness and a breakdown voltage surpassing traditional SiO₂. Capacitance measurements in a Metal–Insulator–Metal (MIM) structure across 50–150 kHz reveal stable dielectric behavior, particularly in thinner flakes. Dielectric constants averaged 9.8 for 40–44 nm thick CdPS₃ and 8.5 for 115–119 nm thick CdPS₃, respectively. The breakdown voltage analysis was conducted up to 200 V, and cryogenic testing at 4 K confirms its robustness under extreme conditions. These findings position CdPS₃ as a stable high-κ dielectric material suitable for energy storage, sensors, and quantum devices, where minimizing dielectric loss is crucial for maintaining coherence and device efficiency.