Research – YPChiu XSTM Group

Research Topics

Interface Science by Cross-sectional Scanning Tunneling Microscopy

Scanning tunneling microscopy(STM), is a powerful tool to probing the electronic structure of materials in atomic scale. In our lab, we use STM to measure the materials heterostructure, such as complex oxides system, superconductors, photovoltaics, and electronic device. In this way, the band alignment and interface property like 2D electron gas can be directly measure and analysis.

Selected Publications:

Hsu, C. C., Huang, B. C., Schnedler, M., Lai, M. Y., Wang, Y. L., Dunin-Borkowski, R. E., … & Chiu, Y. P. (2021). Atomically-resolved interlayer charge ordering and its interplay with superconductivity in YBa2Cu3O6. 81. Nature Communications, 12(1), 1-8.

Chen, W. C., Chen, C. Y., Lin, Y. R., Chang, J. K., Chen, C. H., Chiu, Y. P., … & Chen, L. C. (2019). Interface engineering of CdS/CZTSSe heterojunctions for enhancing the Cu2ZnSn (S, Se) 4 solar cell efficiency. Materials Today Energy, 13, 256-266.

Liu, H. J., Wang, J. C., Cho, D. Y., Ho, K. T., Lin, J. C., Huang, B. C., … & Chu, Y. H. (2018). Giant photoresponse in quantized SrRuO3 monolayer at oxide interfaces. ACS Photonics, 5(3), 1041-1049.

Tra, V. T., Chen, J. W., Huang, P. C., Huang, B. C., Cao, Y., Yeh, C. H., … & Chu, Y. H. (2013). Ferroelectric control of the conduction at the LaAlO3/SrTiO3 heterointerface. Advanced Materials, 25(24), 3357-3364.

Chiu, Y. P., Huang, B. C., Shih, M. C., Shen, J. Y., Chang, P., Chang, C. S., … & Kwo, J. (2011). Atomic-scale determination of band offsets at the Gd2O3/GaAs (100) hetero-interface using scanning tunneling spectroscopy. Applied Physics Letters, 99(21), 212101.

Chiu, Y. P., Chen, B. C., Huang, B. C., Shih, M. C., & Tu, L. W. (2010). Scanning tunneling microscopy and spectroscopy of the electronic structure of dislocations in GaN/Si (111) grown by molecular-beam epitaxy. Applied Physics Letters, 96(8), 082107.

Low-dimensional Materials Electronic Structure

Low-dimensional materials is a group of materials with the size in nanometer scale, and can be classified into 2D, 1D and 0D materials. When things go down to low-dimension, the physics phenomena become very fascinating and the mechanism behind them still need to be investigated. STM allows for the creation of high-resolution maps of the local density of electronic states (LDOS) on the surface of a material, which can provide detailed information about the electronic structure at the atomic scale. This can be particularly useful for studying the electronic properties of low-dimensional materials, such as 2D materials and nanostructures, which have unique and often unusual electronic properties due to their reduced dimensionality.

Selected Publications:

Huang, J. K., Wan, Y., Shi, J., Zhang, J., Wang, Z., Wang, W., … & Li, S. (2022). High-κ perovskite membranes as insulators for two-dimensional transistors. Nature, 605(7909), 262-267.

Siao, M. D., Shen, W. C., Chen, R. S., Chang, Z. W., Shih, M. C., Chiu, Y. P., & Cheng, C. M. (2018). Two-dimensional electronic transport and surface electron accumulation in MoS2. Nature communications, 9(1), 1-12.

Hazut, O., Huang, B. C., Pantzer, A., Amit, I., Rosenwaks, Y., Kohn, A., … & Yerushalmi, R. (2014). Parallel p–n junctions across nanowires by one-step ex situ doping. ACS nano, 8(8), 8357-8362.

Light-modulation STM for Optoelectronic Materials

For semiconductors, lights can excite the carriers from valence band to conduction band, and sometimes, it can even change the electronic structure or the lattice structure. In our group, we use LM-STM to study the optoeletronic materials, such as solar cell, perovskites, and low-dimensional materials.

Selected Publications:

Huang, P. C., Huang, S. K., Lai, T. C., Shih, M. C., Hsu, H. C., Chen, C. H., … & Wang, Y. C. (2021). Visualizing band alignment across 2D/3D perovskite heterointerfaces of solar cells with light-modulated scanning tunneling microscopy. Nano Energy, 89, 106362.

Chen, H. Y., Hsu, H. C., Huang, C. C., Li, M. Y., Li, L. J., & Chiu, Y. P. (2022). Directly Visualizing Photoinduced Renormalized Momentum-Forbidden Electronic Quantum States in an Atomically Thin Semiconductor. ACS nano.

Hsu, H. C., Huang, B. C., Chin, S. C., Hsing, C. R., Nguyen, D. L., Schnedler, M., … & Chiu, Y. P. (2019). Photodriven dipole reordering: Key to carrier separation in metalorganic halide perovskites. ACS nano, 13(4), 4402-4409.