Effects of post-growth treatment and coating with ultrathin metal layers on the band bending and field electron emission of diamond films

Abstract

Band bending formation on thin nanocrystalline diamond films and field electron emission after post-growth treatments was investigated. It was found that treatment of the diamond surface with hydrogen plasma substantially decreases the density of point defects, forms the downward band bending and enhances the field electron emission from the films. In the case of an argon plasma treated diamond surface, new point defects were induced and their energy distribution was changed. Nevertheless, the downward band bending was formed and the field electron emission was enhanced similar to the H–plasma-treated diamond surface with minor density of defects. These effects were interpreted in terms of the electrical dipole formation on the plasma treated diamond surfaces. Coating the diamond films with ultrathin metal (Ni, Ti) layers revealed the dependence of the band bending and field emission behavior on the type and thickness of the metal used. The deposition of a few monolayers of Ni on the diamond surface was found to raise the position of the Fermi level relative to the valence band maximum and cause the downward band bending, reducing the field emission threshold. It was suggested that the charge of the surface dipoles on the metal coated diamond surfaces (as in the case of the H and Ar plasma treatments) plays a key role in the band bending formation.

Charge-based deep level transient spectroscopy of B-doped and undoped polycrystalline diamond films

“…6) E a = 0.038 eV, suggesting a similar origin. For all samples, captured cross section r n;p was approximately 1 9 10 -21 -1 9 10 -23 cm 2 , which are characteristic of points defects such as vacancies or dangling bonds [29]. B-related acceptor states have much larger activation energies [31], and their contribution to the electrical properties is not directly observed in measured, in this work, temperature range.…”

“…If the ratio t 2 /t 1 = a and will be kept constant, then s m will be equal to s m ¼ t 1 ða À 1Þ=lna, and the maximum of the functional dependence of DQ(s m ) can be used to determine the trapping (donor or acceptorlike) center parameters e n;p . Taking a = 2, i.e., s m ¼ t 1 =ln2, we will have [29]:…”

“…In this method, the trapped charge transient process is measured by the voltage or light stimulation. The Q-DLTS method used in present work is described in details elsewhere [27][28][29].…”

Charge deep level transient spectroscopy of electron traps in MOVPE grown n‐GaN on sapphire

“…It is therefore desirable to measure defect properties by using different techniques. Charge deep level transient spectroscopy (Q-DLTS) has been shown to be a useful alternative technique for studying the defects [13][14][15]. In this report, we have used Q-DLTS to measure electron traps in n-GaN, using rate windows 10…”

Investigation of defects in organic semiconductors by charge based Deep Level Transient Spectroscopy (Q‐DLTS)

“…2.2 Analysis of Q-DLTS spectra Assuming a discrete trap level E T , the charge release rate for holes or electrons at temperature T is given by [7,8]:…”