Investigation of an n− layer in a silicon fast recovery diode under applied bias voltages using Kelvin probe force microscopy

• Published in: Japanese Journal of Applied Physics Vol. 57; no. 8S1; pp. 8 - 12
• Main Authors: Uruma, Takeshi, Satoh, Nobuo, Yamamoto, Hidekazu, Iwata, Futoshi
• Format: Journal Article
• Language: English
• Published: Tokyo The Japan Society of Applied Physics 01-08-2018; Japanese Journal of Applied Physics
• Subjects: Atomic force microscopy; Bias; Frequency modulation; Image contrast; Microscopy; Object recognition; Recovery; Silicon; Voltage drop
• ISSN: 0021-4922; 1347-4065
• DOI: 10.7567/JJAP.57.08NB11

We have imaged an n− layer of a commercial silicon fast recovery diode (Si-FRD) under applied bias voltages using frequency modulation atomic force microscopy and Kelvin probe force microscopy. It was possible to image the potential contrast of the exposed active region surface of the Si-FRD owing to the dominant behavior of carriers induced by applying the bias voltages. Under applied reverse bias voltages, potential contrasts at a pn− junction were recognized in potential images. At the applied forward bias voltage of 1.5 V, a potential drop at an n−n interface under conductivity modulation was clearly observed in a potential image. From the distance between the pn− junction and the n−n interface, the n− layer width of a power device was determined to be 36.6 µm.