Dopant activation and photoresponses of boron-doped silicon by self-assembled molecular monolayers

Jing Fu,Hao Wei,Kaixiang Chen,Xuejiao Gao,Shannan Chang,Kanru Zhi,Yaping Dan

doi:10.1063/1.5134118

Abstract

Self-assembled molecular monolayer doping is an emerging doping technique. In this work, we investigated the activation rate and photoresponses of boron doped silicon by self-assembled molecular monolayer doping. By using low temperature Hall effect measurements and by secondary ion mass spectroscopy, we find that the activation rate of boron in these samples is in the range of 91%–54%, depending on the doping concentration. Interestingly, the photoresponsivity of the boron doped samples is also significantly higher than that of the phosphorus doped samples even though the same doping technique is used. The intriguing photoresponses are closely related to the trapping of photogenerated minority carriers by the defects in the p-type silicon.

Highlights

Monolayer doping (MLD) is an emerging technique for controlled doping at nanoscale.1,2 Compared with ion implantation, MLD creates no lattice damage3,4 and is capable of forming conformal doping for 3-dimensional field effect transistors.5,6 In MLD, the dopant molecules are first immobilized on a cleaned wafer surface
We previously showed that the defects of interstitial carbon and substitutional phosphorus pairs (Ci-Ps) can electrically deactivate phosphorus dopants with an activation rate of ∼80%
The cleaned silicon surface reacted with the allylboronic acid pinacol ester (ABAPE) in 1, 3, 5-mesitylene solution at a temperature of 160 ○C for 48 h [Fig. 1(b)]

Summary

Introduction

Monolayer doping (MLD) is an emerging technique for controlled doping at nanoscale.1,2 Compared with ion implantation, MLD creates no lattice damage3,4 and is capable of forming conformal doping for 3-dimensional field effect transistors.5,6 In MLD, the dopant molecules are first immobilized on a cleaned wafer surface. We investigated the dopant activation and photoresponses of silicon samples doped via self-assembled molecular monolayer doping. This is because the defects in the p-type silicon (boron doped) are unfilled and have a high chance to capture photogenerated minority electrons, inducing a strong photoresponse.

Results

Conclusion