Low Temperature Characterization of Dielectric Properties of Complex Oxide Heterostructures on Silicon

Thin film heterostructures of piezoelectric materials are essential building blocks for hybrid microwave-acoustic quantum devices. Due to the large piezoelectric and electro-optic coefficients, complex oxides such as barium titanate (BTO) are of particular interest for such applications. However, on-chip integration of BTO into devices requires growth as thin films on conventional substrates such as Si. Rapid characterization of the dielectric properties of BTO-on-Si (BTO/Si) heterostructures is critical to the iterative process of maximizing their piezoelectric responses. Here, we demonstrate a cryogenic system for rapid characterization of electrical properties of dielectric materials such as BTO/Si. The system is built around a GM cryocooler that reaches its base temperature < 3 hours. Our system is equipped with a capacitance bridge and electrometers to evaluate various electrical properties of the samples. Using this system, we successfully measured the dielectric constant of several BTO/Si heterostructures from 300K to 10K. Our system is capable of characterizing up to 4 samples daily. The fast piezoelectric characterization feedback will be key to our team's effort in developing low-defect heterostructures for hybrid quantum devices.