Laser thermal annealing of Ge, optimized for highly activated dopants and diode ION/IOFF ratios

Abstract

The authors compared the influence of laser thermal annealing (LTA) and rapid thermal annealing (RTA) on dopant activation and electrical performance of phosphorus and arsenic doped n+/p junction. High carrier concentration above 10²⁰ cm^-3 as well as an I_ON/I_OFF ratio of approximately 10⁵ and ideality factor (n) approximately 1.2-1.5 was achieved with LTA. However RTA revealed very high I_ON/I_OFF ratio approximately 10⁷, and n close to 1. Non ideal behavior in LTA diodes is attributed to existence of deep level defects in the junction, contributing to leakage current. Meanwhile ideal behavior of RTA diodes is due to removal of defects in the junction during the high thermal budget.