Enhancing the Performance of Germanium Channel nMOSFET Using Phosphorus Dopant Segregation

• Published in: IEEE electron device letters Vol. 35; no. 1; pp. 6 - 8
• Main Authors: CHEN, Che-Wei, TZENG, Ju-Yuan, CHUNG, Cheng-Ting, CHIEN, Hung-Pin, CHIEN, Chao-Hsin, LUO, Guang-Li, WANG, Pei-Yu, TSUI, Bing-Yue
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.01.2014; Institute of Electrical and Electronics Engineers
• Subjects: Applied sciences; dopant segregation; Electronics; Exact sciences and technology; Germanium; Junctions; Leakage currents; Logic gates; MOSFET; MOSFET circuits; NiGe; nMOSFET; Performance evaluation; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Shottky barrier height; Transistors; Performance evaluation; MOS technology; nMOSFET; High strength current; High performance; MOSFET; n channel; Phosphorus; Fermi level; Shottky barrier height; Drain current; Germanium; Leakage current; dopant segregation; Barrier height; NMOS technology; NiGe; Impurity segregation; Transconductance
• ISSN: 0741-3106; 1558-0563
• DOI: 10.1109/LED.2013.2291774

In this letter, we present a high performance Ge n-channel metal-oxide-semiconductor field-effect transistor (MOSFET) with a NiGe Schottky junction source/drain fabricated using phosphorus dopant segregation. Phosphorus atoms were implanted into NiGe and then driven toward the NiGe/p-Ge interface to depin the Fermi level and form a Schottky junction. A high effective barrier height (Φ Bp ) of 0.57 eV, resulting in a high junction current ratio of at the applied voltage |V a | = ±1 V. The nMOSFET exhibited a high I ON /I OFF ratio of ~ 8×10 3 (I D ), ~ 10 5 (I S ), and a subthreshold swing of 138 mV/decade. The nMOSFET developed in this letter exhibited greater transconductance and a drain leakage current that is more than two orders of magnitude lower compared with nMOSFETs with the conventional n + /p junction.