Band bending mechanism for field emission in wide-band gap semiconductors

Abstract

A theoretical model based on the band bending theory was developed for explaining the field-emission mechanism of wide-band gap semiconductors (WBGSs). It was shown that the maximum value of the band bending, which is nearly linearly proportional to the band gap of WBGSs, may amount to a few eV. Furthermore, the calculated field-emission energy distribution combined with the band bending analyzed on cubic boron nitride (c-BN) as typical one of WBGSs, indicated that the electron emission originates from the conduction band minimum resulting from the band bending. These results present a perspective to explain the field-emission mechanism, in which it is considered that the band bending, as well as the negative electron affinity, is of equal importance to the excellent field emission performances of WBGSs.

Field Emission of Electron Anions Clathrated in Subnanometer‐Sized Cages in [Ca24Al28O64]4+(4e–)

“…[23] This effect is enhanced for wider bandgap materials and the u s value may be » 3 eV for a bandgap of » 6 eV at an electric field of 1 V nm ±1 . [24] We speculate that a low carrier density layer is formed near the sample surface since partial oxidation of the thin surface layer is unavoidable when the sample is transferred to the measurement chamber, which would cause a large surface band bending when an external electric field is applied. Further, the electric field may deform the cage structure of C12A7, [15,16] which also changes the surface electronic structure and enhances electron emission.…”

“…was used to exclude grain-boundary effects [27]. An 0.6 mm thick C12A7 singlecrystal plate [28] was sealed with metal calcium shots in a silica glass tube under vacuum (» 1 Pa) and then heated at 700 C for 240 h (Ca treatment) to produce [Ca 24 …”

Universal characteristics of resonant-tunneling field emission from nanostructured surfaces

“…In addition to the energy barrier between electronic states in the nanostructure (N) and vacuum (V), quantum confinement gives rise to a further barrier at the substrate-nanostructure (S-N) interface. Electric-field penetration into the semiconductor material leads to band bending 15,16 and the formation of 2D bound states at both interfaces. The evolution of boundstate formation is illustrated in Fig.…”

Field emission properties of amorphous GaN ultrathin films fabricated by pulsed laser deposition

“…Therefore, our experiment results that ultrathin film has much better performance than thicker film in field emission directly prove Binh's theoretical analysis [22] that with an ultra-thin film coating, the field emission characteristic will increase prominently. Moreover, our results on a-GaN are much better than Binh's theoretical analysis on TiO 2 [22] , because GaN has a larger band gap than TiO 2 , which may lead to a more significant band bending [23] . Thus, field emission characteristic can be enhanced further, even stronger than some of the one-dimensional materials [7,21] .…”