Field emission properties of diode devices based on amorphic diamond-Si heterojunctions

Abstract

Microscopic and macroscopic field emission properties of amorphic diamond films on n- and p-type silicon substrates were studied by combined scanning tunneling microscopy/spectroscopy and integral field emission I–V measurements. Microscopic scanning tunneling spectroscopy showed that amorphic diamond films on n-Si have lower threshold voltage and higher emission current than amorphic diamond films on p-Si. The observed rectification characteristics suggest that amorphic diamond on n-Si is an ideal forward-biased p-n junction cold cathode emitter; however, there is no significant difference between these two structures by integral field emission I–V measurements. Conversion of the smooth amorphic diamond film into porous sp3/sp2 composites with sharp features under electric fields higher than 50 V/μm, followed by preferred electron emission from the porous composite sites of high transconductance, was believed to be the cause.

Enhanced field emission current from diamond-like carbon films deposited by laser ablation of C60fullerene

“…The field emission of electrons from diamond-like carbon (DLC) films deposited by different methods has been reported [1][2][3][4][5][6][7][8][9][10]. Two forms of DLC films, amorphous carbon (a-C) [1][2][3][4][5][6][7][8] and hydrogenated amorphous carbon (a-C:H) [9,10], have been studied. DLC films consist of sp 2 coordinated clusters embedded in an sp 3 coordinated carbon matrix [10][11][12].…”

“…The volume fraction of sp 3 bonds is increased by the hydrogenation of films [11,12], and a-C:H films emit electrons at a lower field than a-C films [8,9]. It has been reported that the electron emission from DLC depends on several factors, such as the low work function of sp 3 clusters, field enhancement at emission sites by the formation of a nano-columnar structure of carbon films and doping and/or defects in sp 3 clusters [1][2][3][4][5][6][7][8][9][10]. However, the emission current from DLC emitters has been limited to several tenths of a micro-ampere.…”

“…However, the emission current from DLC emitters has been limited to several tenths of a micro-ampere. The stability of DLC films is poor at high current densities in which efficient emission sites of sp 3 clusters can be transformed to sp 2 clusters as a result of heating at higher current densities [4,5]. In addition, the reduction of the emission current in highly resistive films has been considered as a space charge or bulk limiting phenomena [9,13].…”

Determination of the valence band offset of a heterojunction using low energy yield spectroscopy

“…One of the most interesting characteristics of amorphous carbon films is the variability of their electronic, optical and mechanical properties. They are governed by the relative concentration of the three different carbon bond configurations, sp 1 , sp 2 and sp 3 , that can exist simultaneously in a carbon film. During preparation, it is possible to vary this ratio, thereby tailoring the material for various important technological applications.…”

“…During preparation, it is possible to vary this ratio, thereby tailoring the material for various important technological applications. The characteristics of the heterojunctions made by depositing amorphous carbon on crystalline silicon (c-Si) are a subject of increasing interest because of their potential application in a variety of electronic devices [1][2][3][4]. A fundamental problem is that of understanding the way in which the band gaps of the constituent semiconductors are aligned when the junction is formed.…”