The Effect of Gas Absorption on Multilayer Black Phosphorus Field Effect Transistor

Multilayer black phosphorus (BP) is drawing much attention recently due to its reported high mobility (up to 1000 cm$^{2}$V$^{-1}$s$^{-1})$ and on/off ratio (up to 10$^{5})$ as the channel material for field effect transistor (FET). We investigated the interplay between the electrical response of high performing BPFET and gas adsorbate introduced to its surrounding environment. Different type of gas including CO2, H2O, Ethanol, CO, NO, NH3, etc. has been tested. We observed that the absorption of gas molecules generally reduces the overall on-state conductance of the device with an order of 10 $\sim$ 100. And such reduction can be fully recovered by purging with inert gas or baking at mild temperature (about 100$^{\circ}$C). The absorption dynamics and detailed mechanism are also been investigated. We conclude that multilayer black phosphorus is an excellent material for chemical sensing.