Semiconductor devices are required to have high performance and versatility with the advent of the 4th Industrial Revolution so that the size of semiconductor unit devices is continuously decreasing. As the size of the entire device approaches to the size of several tens of nm, the portion occupied by the heterogeneous junction in the terminal device is not small even if the interface size is only sub-nm. In the past, it was sufficient to understand the behavior of the device by merely analyzing the electronic structure of each material. However, nowadays, it has become essential to understand the defect structure of the interface and the electron transport behavior at the interface.
The goal of this work is to describe the electronic band structure of various electronic devices according to the metal-insulator-metal capacitor, Schottky diode, p-n diode, and quasi-2DEG channel between heterojunction oxides, respectively. The defects of the valence band and the core-level analysis of each element was carried out using various spectroscopic analysis. The behaviors at each interface were explained by suggesting the band alignment model by X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, energy electron loss spectroscopy, spectroscopic ellipsometry, and internal photoemission spectroscopy. In the case of the MIM capacitor, it is possible to compare and analyze the behavior with an intrinsic level device through analysis of defect behavior at the working device level.
As a result, the phenomena of electronic behavior and electrical characteristics of various electronic devices are explained through the understanding of the interface of electronic structure. Besides, the quasi-2DEG channel was implemented based on the knowledge of the interfaces of these electronic structures, and the mechanism of 2DEG expression has been clarified.