講演情報
[14p-K507-6]Direct Imaging of the p-n Interface in Semiconductor Devices by Operando Energy-Resolved Photoemission Electron Microscopy
〇(P)Elizaveta Pyatenko1, Shunsuke Nozawa1, Keiki Fukumoto1 (1.KEK IMSS)
キーワード：
p-n junction、tunnel diode、electronic properties
To improve the properties of semiconductor-based devices such as transistors and solar cells, it is important to obtain a detailed understanding of the energy band alignment, as well as to visualize the movement of charge carriers across the interface. Although the underlying theory of semiconductors is well-established, the main characterization techniques are electrical measurements such as current-voltage characteristics and capacitance-voltage profiles. It is crucial to develop a method to directly visualize the changes in the energy band structure, as well as the depletion layer width, during device operation. Our operando photoelectron microscopy (PEEM) technique allows to simultaneously obtain spatial, energy, and time-resolved information, and has been applied to study the charge-carrier transport mechanism in organic antiambipolar transistors.
In this study, we employed operando PEEM to study the cross-section of the p-n interface of a wafer-bonded GaAs backward diode, under forward and reverse bias operation. Using operando energy-resolved PEEM, we could visualize the external voltage dependent energy band alignment. In addition to determining the conduction band minima of the p- and n-type regions, we observed additional spectral signatures in the n-region, which we attributed to the tunneling of electrons under reverse bias. Moreover, the depletion layer and its widening under increasing reverse bias voltage was directly visualized in the PEEM images. Our operando PEEM method can be applied to study p-n junctions, as well as the Schottky barrier in metal-semiconductor junctions in various devices, leading to a better understanding and an improvement of their electronic properties.
In this study, we employed operando PEEM to study the cross-section of the p-n interface of a wafer-bonded GaAs backward diode, under forward and reverse bias operation. Using operando energy-resolved PEEM, we could visualize the external voltage dependent energy band alignment. In addition to determining the conduction band minima of the p- and n-type regions, we observed additional spectral signatures in the n-region, which we attributed to the tunneling of electrons under reverse bias. Moreover, the depletion layer and its widening under increasing reverse bias voltage was directly visualized in the PEEM images. Our operando PEEM method can be applied to study p-n junctions, as well as the Schottky barrier in metal-semiconductor junctions in various devices, leading to a better understanding and an improvement of their electronic properties.