Direct observation of dopant distribution in GaAs compound semiconductors using phase-shifting electron holography and Lorentz microscopy

作者：Sasaki Hirokazu^*; Otomo Shinya; Minato Ryuichiro; Yamamoto Kazuo; Hirayama Tsukasa

来源：Journal of Electron Microscopy, 2014, 63(3): 235-241.

DOI：10.1093/jmicro/dfu008

• electron holography
• Lorentz microscopy
• dopant distribution
• GaAs
• FIB
• semiconductor

Phase-shifting electron holography and Lorentz microscopy were used to map dopant distributions in GaAs compound semiconductors with step-like dopant concentration. Transmission electron microscope specimens were prepared using a triple beam focused ion beam (FIB) system, which combines a Ga ion beam, a scanning electron microscope, and an Ar ion beam to remove the FIB damaged layers. The p-n junctions were clearly observed in both under-focused and over-focused Lorentz microscopy images. A phase image was obtained by using a phase-shifting reconstruction method to simultaneously achieve high sensitivity and high spatial resolution. Differences in dopant concentrations between 1 x 10(19) cm(-3) and 1 x 10(18) cm(-3) regions were clearly observed by using phase-shifting electron holography. We also interpreted phase profiles quantitatively by considering inactive layers induced by ion implantation during the FIB process. The thickness of an inactive layer at different dopant concentration area can be measured from the phase image.

• 出版日期2014-6