Milliseconds Thermal Processing of Boron Hyperdoped Germanium

Abstract

P‐type hyperdoped germanium (Ge) has attracted significant attention for the development of superconducting semiconductors. However, the limited solid solubility of acceptors, especially boron (B), in Ge makes hyperdoping challenging. Herein, a systematic study on the electrical properties of boron‐implanted germanium is presented with an atomic concentration beyond 10 at%. The B‐implanted Ge was annealed by millisecond flash lamp annealing (ms‐FLA) with different parameters. The results indicate that millisecond solid phase epitaxy ensures the electrical activation of B much above the solubility limit with hole concentration as high as 2 × 1021 cm−3 and low‐temperature sheet resistance of 13 Ω sq−1 which is promising for superconductivity. It is also shown that millisecond annealing effectively suppresses the B diffusion and provides much higher activation efficiency of acceptors compared to conventional annealing methods.