Quantum Size Effects on the Chemical Sensing Performance of   Two-Dimensional Semiconductors
  We investigate the role of quantum confinement on the performance of gas sensors based on two-dimensional InAs membranes. Pd-decorated InAs membranes configured as H2 sensors are shown to exhibit strong thickness dependence, with ~100x enhancement in the sensor response as the thickness is reduced from 48 to 8 nm. Through detailed experiments and modeling, the thickness scaling trend is attributed to the quantization of electrons which favorably alters both the position and the transport properties of charge carriers; thus making them more susceptible to surface phenomena. 
Junghyo Nah, S. Bala Kumar, Hui Fang, Yu-Ze Chen, Elena Plis, Yu-Lun   Chueh, Sanjay Krishna, Jing Guo and Ali Javey
cond-mat.mes-hall quant-ph