[EDP1] SQUID, Detector, Metrology, Novel Device

[EDP1-12] Preliminary Electrical Characterization of BSCCO/ZnO and BSCCO/Cu_xO Heterojunctions Prepared via MOD Method

*Yasuyuki Yamada¹, Masato Nobushima¹, Shu Ikura¹, Hiromu Kasai¹ (1. National Institute of Technology,Oyama College (Japan))

Keywords:

BSCCO,MOD method,heterojunction,semiconductor,electrical characterization

Superconductor/semiconductor interfaces have attracted sustained interest due to their potential to host novel quantum transport phenomena. In particular, the Josephson plasma (JP) mode in Bi₂Sr₂CaCu₂O_8+δ (BSCCO) is a key feature for high-frequency superconducting devices and emerging superconducting photonic applications. Conventional excitation methods for the JP mode, such as DC bias and terahertz (THz) irradiation, face limitations including thermal dissipation, restricted spatial resolution, and complex system configurations. As an alternative, optical excitation via superconductor/semiconductor heterojunctions offers a promising route for localized and efficient carrier injection with reduced thermal load, potentially enabling new device architectures that integrate superconductivity and photonics.In this study, we report on the fabrication and preliminary evaluation of heterostructures composed of BSCCO thin films and overlying layers of p-type copper oxide (Cu_xO) and n-type zinc oxide (ZnO), prepared using the metal-organic decomposition (MOD) method. MOD is advantageous for its high compositional control, low environmental impact, and compatibility with non-vacuum processing. However, multilayer fabrication requires careful optimization of thermal treatment conditions to prevent degradation of the underlying superconducting layer. Our previous results confirmed that Cu_xO forms ohmic contact with BSCCO at both room temperature and 77 K, and that all samples exhibit stable superconducting transitions above liquid nitrogen temperature.Thin films were deposited by spin coating metal-organic precursor solutions followed by thermal annealing in a muffle furnace. The precursor solutions—SK-BSCCO008, Cu-03A, and Zn-05—were obtained from High Purity Chemical Laboratory Co., Ltd. Substrates used were MgO (100) or SrTiO₃ (100), with dimensions of 10×10×0.5 mm. Spin coating was performed using the ASC-300 system (Able Co., Ltd.), and annealing was conducted using the KDF-P70 furnace (Denken Co., Ltd.). After forming the BSCCO base layer, the second semiconductor layer was patterned using masking tape and deposited. Silver paste was used to form electrodes on exposed BSCCO regions and manually on the top semiconductor layer.Electrical characterization included van der Pauw measurements and local current–voltage analysis. When multiple electrodes were placed on the ZnO layer, nonlinear and rectifying behavior was observed at 77 K in one region. This suggests the spontaneous formation of a diode-like junction capable of selective carrier transport. However, the origin of this behavior remains unclear—it may arise from intrinsic properties of the BSCCO/ZnO interface, compositional inhomogeneity in the ZnO layer, or the geometry of the electrodes. Future work will involve detailed spatial mapping of electrical properties to elucidate the physical origin of the observed phenomena.