Pristine PN junction toward atomic layer devices

Abstract

In semiconductor manufacturing, PN junction is formed by introducing dopants to activate neighboring electron and hole conductance. To avoid structural distortion and failure, it generally requires the foreign dopants localize in the designated micro-areas. This, however, is challenging due to an inevitable interdiffusion process. Here we report a brand-new junction architecture, called “layer PN junction”, that might break through such limit and help redefine the semiconductor device architecture. Different from all existing semiconductors, we find that a variety of van der Waals materials are doping themselves from n- to p-type conductance with an increasing/decreasing layer-number. It means the capability of constructing homogeneous PN junctions in monolayers’ dimension/precision, with record high rectification-ratio (>105) and low cut-off current (<1 pA). More importantly, it spawns intriguing functionalities, like gate-switchable-rectification and noise-signal decoupled avalanching. Findings disclosed here might open up a path to develop novel nanodevice applications, where the geometrical size becomes the only critical factor in tuning charge-carrier distribution and thus functionality.

Heteroatoms (Si, B, N, and P) doped 2D monolayer MoS2for NH3gas detection

“…6,7 Hence, various health agencies worldwide have fixed the maximum limit of ammonia in workplaces at 25 ppm. 8 Though it is a challenging task to achieve gas sensing under extreme environmental conditions, molybdenum disulfide (MoS 2 ), as a typical transition metal with its characteristic of higher charge carrier mobility, has offered us a great opportunity to surmount these challenges to some extent. 9,10…”

“…6,7 Hence, various health agencies worldwide have xed the maximum limit of ammonia in workplaces at 25 ppm. 8 Though it is a challenging task to achieve gas sensing under extreme environmental conditions, molybdenum disulde (MoS 2 ), as a typical transition metal with its characteristic of higher charge carrier mobility, has offered us a great opportunity to surmount these challenges to some extent. 9,10 In line with the development of experimental strategies, density functional theory (DFT) has recently been used by many scientists employing theoretical calculations to predict and understand the mechanistic behaviour, sensitivity and conductivity of the gas sensing ability of many materials.…”

p-Type ohmic contact to MoS2via binary compound electrodes

“…13 Ambipolar contact to MoS 2 can be achieved by different elemental metals with different work functions, 14 or with layer-number engineering of defect states. 15…”

“Clean” doping to advance 2D material phototransistors

“…Furthermore, Wang et al reported controllable thickness-modulated doping in a series of 2D materials, including wide and narrow bandgap materials 5 . Moreover, thickness-modulated heterojunction and avalanche photodetectors are successfully fabricated and exhibit high performance 6 – 8 .…”