Electrical activities of sulfur dopants in GaAs introduced by self-assembled molecular monolayers

Self-assembled molecular monolayer doping remains as a research focus for its nature of being conformal, nondestructive, and self-limiting. However, the carrying molecules may contaminate the substrate and electrically deactivate the dopants. In this work, we investigate the electrical activities of sulfur dopants in GaAs introduced by the self-assembled molecular monolayer doping technique. The results from secondary ion mass spectrometry and low-temperature Hall measurements show that the activation energy of sulfur dopants is 68 meV, and that 91% of these dopants introduced into GaAs by the self-assembled molecular monolayer doping technique are electrically active. The impact of the carrying molecular contamination is minimal. We employ this monolayer doping technique to create a PN junction diode on a p-type GaAs substrate. The PN junction diode exhibits an outstanding performance with an ideality factor of 1.26 and a rectification ratio up to 104 within the bias of ±0.6 V.