Dependence of Schottky Barrier Height on Donor Concentration

Abstract

Schottky barrier heights of Au contacts to n-type Si with either etch-polished or vacuum-cleaved interfaces are independent of donor concentration within an experimental uncertainty of about ±0.05 eV for 1014 cm−3≤ND≤1019 cm−3. Within the same uncertainty and over the same doping range, barrier heights determined from capacitance using the standard formula are equal to those determined from photoemission thresholds. A theory for deducing barrier heights from photoemission thresholds that includes the effects of tunneling and image force is presented. The results are interpreted in terms of a simple model for the interface, which is characterized by the thickness d and dielectric constant κ′ of the interfacial film and the density nss of interface states. The insensitivity of the barrier height to the quantity of space charge leads to the following limit on the interfacial parameters: (k′/d)+1.8×10−6nss≥3.8×108 cm−1for d in cm, and nss in cm−2 eV−1.

Doping dependence of the barrier height and ideality factor of Au/n-GaAs Schottky diodes at low temperatures

“…Thermionic emission (TE) theory is normally used to extract the SBD parameters [1][2][3][4][5][6][7], however, there have been several reports of certain anomalies [4,[7][8][9] at low temperatures. The ideality factor and barrier height determined from the forward bias current-voltage ðI2VÞ characteristics on the basis of the TE mechanism were found to be a strong function of temperature and doping concentration [5,[9][10][11][12][13][14][15][16][17][18][19][20].…”

“…There is no scientific basis for such a proposal [23], however. Just as for the ideality factor, lowering of the SBH by image forces, interface states, and thermionic field emission (TFE) has frequently been invoked to explain the doping-level dependence of F I2V [13,15,20]. Explanations of the possible origin of such anomalies have been proposed, taking into account the interface state density distribution [17,24], quantum-mechanical tunneling [3,24,25], image force lowering [25], and most recently the lateral distribution of barrier height inhomogeneities [19,[26][27][28].…”

Conducting atomic force microscopy studies of nanoscale cobalt silicide Schottky barriers on Si(111) and Si(100)

“…Additionally, a previous study has found that when N D ~ 10 15 cm 3 , the reduction in the barrier height due to image force lowering is less than 0.01 eV [29]. Thus, image force lowering is a negligible effect at the low doping concentrations used in this study.…”

Evidence of Low Schottky Barrier Effects and the Role of Gap States in the Electronic Transport through Individual CoSi2 Silicide Nanoislands at Low Temperature (9 K)

“…This should probably induce a small number of dislocation (∼1) along the buried interface of the silicide pads for a typical length of ∼20 nm, similar to what has been observed previously via other techniques. , It is thus possible to exclude that the origin of the observed good conductance at energies lying in the silicon gap is mainly due to a bad boundary reconstruction at the silicide–silicon interface. However, the presence of other states, such as the one induced by dopant or interstitial metal atoms, can act as interface states and can also modify the electronic transport toward the bulk silicon. , Under these conditions, the energy of the intrinsic Schottky barrier height should stay relatively high (Φ B ∼ 0.3 eV) for our experimental condition (9 K) compared to what is measured at room temperature (Φ B ∼ 0.6 eV), because the interface states are similar when the temperature varies. − This is particularly the case if we consider that our silicide islands are grown via reactive deposition epitaxy methods. This implies that a large quantity of interstitial Co atoms has migrated in the subsurface of the silicon sample and subsequently been frozen in place when the growth process is stopped .…”