Encapsulation of phosphorus dopants in silicon for the fabrication of a quantum computer

TL;DR

This study demonstrates precise phosphorus doping in silicon with minimal segregation and high electron mobility, advancing the fabrication of atomic-scale dopant arrays for quantum computing.

Contribution

It introduces a method for phosphorus incorporation in silicon that achieves minimal segregation, complete activation, and high mobility, crucial for quantum computer architectures.

Findings

Minimal dopant segregation of 5 nm

Complete electrical activation at 250°C

High electron mobility of 100 cm²/Vs at 4.2 K

Abstract

The incorporation of phosphorus in silicon is studied by analyzing phosphorus delta-doped layers using a combination of scanning tunneling microscopy, secondary ion mass spectrometry and Hall effect measurements. The samples are prepared by phosphine saturation dosing of a Si(100) surface at room temperature, a critical annealing step to incorporate phosphorus atoms, and subsequent epitaxial silicon overgrowth. We observe minimal dopant segregation (5 nm), complete electrical activation at a silicon growth temperature of 250 degrees C and a high two-dimensional electron mobility of 100 cm2/Vs at a temperature of 4.2 K. These results, along with preliminary studies aimed at further minimizing dopant diffusion, bode well for the fabrication of atomically precise dopant arrays in silicon such as those found in recent solid-state quantum computer architectures.