The bias-dependence change of barrier height of Schottky diodes under forward bias by including the series resistance effect

Abstract

Schottky barrier height shifts depending on the interfacial layer as well as a change of the interface state charge with the forward bias while considering the presence of bulk (semiconductor) series resistance are discussed both theoretically and experimentally. It has been concluded that the barrier height shift or increase in Schottky diodes is mainly due to the potential change across the interfacial layer and the occupation of the interface states as a result of the applied forward voltage. One assumes that the barrier height is controlled by the density distribution of the interface states in equilibrium with the semiconductor and the applied voltage. In nonideal Schottky diodes, the values of the voltage drops across the interfacial layer, the depletion layer and the bulk resistance are given in terms of the bias dependent ideality factor, n, different from those in literature. These values are determined by a formula obtained for and V, by means of change of the interface charge with bias.

The Cu/n-GaAs schottky barrier diodes prepared by anodization process

“…When the SBDs with a thin interfacial layer (MIS) are considered, it is assumed that the forward-bias current of the device is due to thermionicemission current, and it can be expressed as 11,19,20 (1)…”

“…The values of n indicate that the device obeys a metal-interface layer-semiconductor (MIS) configuration rather than ideal Schottky diode. 11,12,[17][18][19][20][21][22][23][24][25][26] is the laterally homogeneous barrier height. Figure 2 shows high-frequency (HF) C-V characteristics for sample CuG3 at 100 kHz.…”

“…As mentioned in Refs. 1,4,5,[8][9][10][11], and 21-26, whether the barrier height increases in the contacts with the interfacial layer depends on the position of the neutral level and interface-state density. If the net increase in the charge is not zero, the increase in positive or negative charge will affect the depletion layer of the semiconductor, thereby affecting the Fermi-level position.…”

“…[1][2][3][4][5] The formation of high-quality Schottky barrier diodes (SBDs) with a low ideality factor using thin interfacial films is one of the essential prerequisites for devices. 1,[5][6][7][8][9][10][11][12][13][14] Furthermore, the metal-insulating semiconductor (MIS) structure is more desirable than the Schottky junction because the former generally has much higher barrier than the latter. In MIS structures, a thin transition-interfacial layer separates the metal from the semiconductor surface.…”

“…To resolve the discrepancy between the barrier-height values expected from the simple Schottky-Mott rule and experimental barrierheight values, Bardeen 8 proposed interface states that determine the position of the Fermi level within the bandgap at the interface, thus the barrier height becomes independent of the metal used. So far, many attempts [9][10][11][12][13][14] have been made to realize a modification of the Schottky barrier height (SBH) using a thin oxide or insulation layer. Moreover, Song et al 15 and Mui et al 16 have studied the experimental data of the GaAs Schottky diodes, considering the image-force lowering effect.…”