The Effect of Aqueous Chemical Cleaning Procedures on Schottky Contacts to N-Type Gaas

1990 ◽  
Vol 181 ◽  
Author(s):  
M. L. Kniffin ◽  
C.R. Helms
Keyword(s):  
Schottky Barrier ◽  
Barrier Height ◽  
Annealing Temperature ◽  
Oxide Thickness ◽  
Schottky Contacts ◽  
Initial Surface ◽  
Chemical Cleaning ◽  
Barrier Heights ◽  
Native Oxides ◽  
Cleaning Procedures

ABSTRACTThe effect of interfacial oxides and impurities left by aqueous chemical cleaning procedures on the n-type Schottky barrier heights of various metal-GaAs contacts have been examined as a function of annealing temperature. The as-deposited barrier heights of metals which are expected to be reactive with respect to the native oxides of GaAs (Mn, Cr, Al and Ti) were the most sensitive to variations in the residual oxide thickness. Omitting the final oxide etch from the cleaning sequence resulted in a 50 to 60 meV reduction in the as-deposited barrier height of these metals. However annealing these contacts at temperatures as low as 175 °C results in a barrier height that is independent of the initial surface clean. In contrast, for metals which are expected to be unreactive with respect to the native oxides of GaAs (Ni, Au, Cu and Ag) the pre-deposition cleaning procedure had little effect on either the as-deposited or the annealed Schottky barrier heights.

Analysis of temperature-dependent Schottky barrier parameters of Cu–Au Schottky contacts to n-InP

2012 ◽  
Vol 90 (1) ◽  
pp. 73-81 ◽  
Author(s):  
V. Lakshmi Devi ◽  
I. Jyothi ◽  
V. Rajagopal Reddy
Keyword(s):  
Schottky Barrier ◽  
Barrier Height ◽  
Gaussian Distribution ◽  
Ideality Factor ◽  
Thermionic Emission ◽  
Schottky Contacts ◽  
Temperature Dependent ◽  
Semiconductor Interface ◽  
Zero Bias ◽  
Barrier Heights

In this work, we have investigated the electrical characteristics of Au–Cu–n-InP Schottky contacts by current–voltage (I–V) and capacitance–voltage (C–V) measurements in the temperature range 260–420 K in steps of 20 K. The diode parameters, such as the ideality factor, n, and zero-bias barrier height, Φb0, have been found to be strongly temperature dependent. It has been found that the zero-bias barrier height, Φb0(I–V), increases and the ideality factor, n, decreases with an increase in temperature. The forward I–V characteristics are analyzed on the basis of standard thermionic emission (TE) theory and the assumption of gaussian distribution of barrier heights, due to barrier inhomogeneities that prevail at the metal–semiconductor interface. The zero-bias barrier height Φb0 versus 1/2kT plot has been drawn to obtain the evidence of a gaussian distribution of the barrier heights. The corresponding values are Φb0 = 1.16 eV and σ0 = 159 meV for the mean barrier height and standard deviation, respectively. The modified Richardson plot has given mean barrier height, Φb0, and Richardson constant, A**, as 1.15 eV and 7.34 Acm−2K−2, respectively, which is close to the theoretical value of 9.4 Acm−2K−2. Barrier heights obtained from C–V measurements are higher than those obtained from I–V measurements. This inconsistency between Schottky barrier heights (SBHs) obtained from I–V and C–V measurements was also interpreted. The temperature dependence of the I–V characteristics of the Au–Cu–n-InP Schottky diode has been explained on the basis of TE mechanism with gaussian distribution of the SBHs.

Comparison of Electrical Characteristics of 4H-SiC(0001) and (000-1) Schottky Barrier Diodes

2006 ◽  
Vol 527-529 ◽  
pp. 927-930 ◽  
Author(s):  
Tomonori Nakamura ◽  
Toshiyuki Miyanagi ◽  
Isaho Kamata ◽  
Hidekazu Tsuchida
Keyword(s):  
Schottky Barrier ◽  
Annealing Temperature ◽  
Schottky Contact ◽  
Schottky Contacts ◽  
Electrical Characteristics ◽  
Schottky Barrier Diodes ◽  
Barrier Heights ◽  
Excess Current ◽  
Low Leakage ◽  
Low Leakage Current

We compared the electrical characteristics of 4H-SiC(0001) and (000-1) Schottky barrier diodes (SBDs), and derived the Schottky barrier heights (Hbs) of Ta, W, Mo, and Pd on {0001}. We investigated the annealing temperature dependence of Hbs in Mo and the W Schottky contacts for (0001) and (000-1). The Hbs are increased by annealing, except for the W Schottky contact on (0001). The yields of 0.25 cm2 as-deposited Mo-SBDs were 93.3% for (0001) and 71.1% for (000-1), respectively. We also demonstrated over 1 cm2 (0001) as-deposited Mo-SBD with a low leakage current, an excellent ideality factor, and no excess current, encouraging the enlargement of the active area in the SBD.

scholarly journals Electrical Properties of Rapidly Annealed Ir and Ir/Au Schottky Contacts on n-Type InGaN

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
V. Rajagopal Reddy ◽  
B. Prasanna Lakshmi ◽  
R. Padma
Keyword(s):  
Barrier Height ◽  
Annealing Temperature ◽  
Schottky Diodes ◽  
Forward Bias ◽  
Interface State ◽  
Schottky Contacts ◽  
Barrier Heights ◽  
Current Voltage ◽  
State Densities ◽  
Optimum Annealing Temperature

The effect of annealing temperature on electrical characteristics of iridium (Ir) and iridium/gold (Ir/Au) Schottky contacts to n-type InGaN have been investigated by means of current-voltage (I-V) and capacitance-voltage (C-V) techniques. It is observed that the barrier height of Ir/n-InGaN and Au/Ir/n-InGaN Schottky diodes increases after annealing at 300∘C for 1 min in N2 ambient compared to the as-deposited. However, the barrier heights are found to be decreased somewhat after annealing at 500∘C for the both Ir and Ir/Au Schottky contacts. From the above observations, it is clear that the optimum annealing temperature for both Ir and Ir/Au Schottky contacts is 300∘C. Moreover, the barrier height (ϕb), ideality factor (n) and series resistance (RS) are determined using Cheung’s and Norde methods. Besides, the energy distribution of interface state densities are determined from the forward bias I-V characteristics by taking into account the bias dependence of the effective barrier height. Based on the above results, it is clear that both Ir and Ir/Au Schottky contacts exhibit a kind of thermal stability during annealing.

Electrical Properties of Inhomogeneous Pt/GaN Schottky Barrier

2008 ◽  
Vol 600-603 ◽  
pp. 1341-1344 ◽  
Author(s):  
Fabrizio Roccaforte ◽  
Ferdinando Iucolano ◽  
Filippo Giannazzo ◽  
Salvatore di Franco ◽  
Valeria Puglisi ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Temperature Dependence ◽  
Schottky Barrier ◽  
Barrier Height ◽  
Ideality Factor ◽  
Schottky Contacts ◽  
Electrical Behavior ◽  
Atomic Force ◽  
Current Voltage ◽  
Local Current

In this work, the electrical properties of Pt/GaN Schottky contacts were studied. The temperature dependence of the barrier height and ideality factor, and the low experimental value of the Richardson’s constant, were discussed considering the formation of an inhomogenous Schottky barrier. Local current-voltage measurements on Pt/GaN contact, performed with a conductive atomic force microscope, demonstrated a Gaussian distribution of the local barrier height values and allowed to monitor the degree of inhomogeneity of the barrier. The presence of defects, terminating on the bare GaN surface, was correlated with the electrical behavior of the inhomogeneous barrier.

Electrical Nanocharacterization of Epitaxial Graphene/Silicon Carbide Schottky Contacts

2014 ◽  
Vol 778-780 ◽  
pp. 1142-1145 ◽  
Author(s):  
Filippo Giannazzo ◽  
Stefan Hertel ◽  
Andreas Albert ◽  
Antonino La Magna ◽  
Fabrizio Roccaforte ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Schottky Barrier ◽  
Barrier Height ◽  
Photoelectron Spectroscopy ◽  
Schottky Contact ◽  
Epitaxial Graphene ◽  
Schottky Contacts ◽  
Specific Contact Resistance ◽  
Monolayer Graphene ◽  
Conductive Atomic Force Microscopy

Epitaxial graphene fabricated by thermal decomposition of the Si-face of silicon carbide (SiC) forms a defined interface to the SiC substrate. As-grown monolayer graphene with buffer layer establishes an ohmic interface even to low-doped (e. g. [N] ≈ 1015 cm-3) SiC, and a specific contact resistance as low as ρC = 5.9×10-6 Ωcm2 can be achieved on highly n-doped SiC layers. After hydrogen intercalation of monolayer graphene, the so-called quasi-freestanding graphene forms a Schottky contact to n-type SiC with a Schottky barrier height of 1.5 eV as determined from C-V analysis and core level photoelectron spectroscopy (XPS). This value, however, strongly deviates from the respective value of less than 1 eV determined from I-V measurements. It was found from conductive atomic force microscopy (C-AFM) that the Schottky barrier is locally lowered on other crystal facets located at substrate step edges. For very small Schottky contacts, the barrier height extracted from I-V curves approaches the value of 1.5 eV from C-V and XPS.

TEMPERATURE DEPENDENCE OF ELECTRICAL CHARACTERISTICS OF Cr/p–Si(100) SCHOTTKY BARRIER DIODES

2008 ◽  
Vol 22 (14) ◽  
pp. 2309-2319 ◽  
Author(s):  
K. ERTURK ◽  
M. C. HACIISMAILOGLU ◽  
Y. BEKTORE ◽  
M. AHMETOGLU
Keyword(s):  
Temperature Dependence ◽  
Schottky Barrier ◽  
Barrier Height ◽  
Thermionic Emission ◽  
Electrical Characteristics ◽  
Schottky Barrier Diodes ◽  
Semiconductor Interface ◽  
Linear Portion ◽  
Barrier Heights ◽  
P Type

The electrical characteristics of Cr / p – Si (100) Schottky barrier diodes have been measured in the temperature range of 100–300 K. The I-V analysis based on thermionic emission (TE) theory has revealed an abnormal decrease of apparent barrier height and increase of ideality factor at low temperature. The conventional Richardson plot exhibits non-linearity below 200 K with the linear portion corresponding to activation energy 0.304 eV and Richardson constant (A*) value of 5.41×10-3 Acm-2 K -2 is determined from the intercept at the ordinate of this experimental plot, which is much lower than the known value of 32 Acm-2 K -2 for p-type Si . It is demonstrated that these anomalies result due to the barrier height inhomogeneities prevailing at the metal-semiconductor interface. Hence, it has been concluded that the temperature dependence of the I-V characteristics of the Cr/p – Si Schottky barrier diode can be successfully explained on the basis of TE mechanism with a Gaussian distribution of the barrier heights. Furthermore, the value of the Richardson constant found is much closer than that obtained without considering the inhomogeneous barrier heights.

Defect Reduction in Si-based Metal-Semiconductor-Metal Photodetectors with Cryogenic Processed Schottky Contacts

2005 ◽  
Vol 864 ◽  
Author(s):  
M. Li ◽  
W. A. Anderson
Keyword(s):  
Schottky Barrier ◽  
Barrier Height ◽  
Dark Current ◽  
Schottky Barrier Height ◽  
Schottky Diodes ◽  
Schottky Contacts ◽  
Metal Deposition ◽  
Active Area ◽  
Electrode Spacing ◽  
Metal Semiconductor Metal

AbstractMetal-Semiconductor-Metal photodetectors (MSM-PD's) and simple Schottky diodes were fabricated using a low temperature (LT) technique to greatly reduce the device dark current. LT processing for metal deposition increased Schottky barrier height by improving the interface between metal and semiconductor to reduce the leakage current of the device. The structure consists of a 20 Å oxide over the active area to passivate surface states, a thicker oxide under contact pads to reduce dark current and the interdigitated Schottky contacts. A comparison was made for Schottky metal deposited with the substrate at 25 °C or -50 °C (LT). The devices fabricated using the LT process had better I-V characteristics compared to detectors fabricated using the standard room temperature (RT) metal deposition technique. The dark current for the LT film was found to be one to three orders lower in magnitude compared to the film deposited at RT. In one case, for example, the dark current was significantly reduced from 1.69 nA to 4.58 pA at 1.0 V. The active area for the device was determined to be 36 × 50 μm2 with 4 μm electrode width and 4 μm electrode spacing. Additionally, LT-MSM-PD's exhibited an excellent linear relationship between the photo-current and the incident light power. The Schottky barrier height for LT processing was found to be 0.79 eV; however, this value was 0.1 eV more than that of the same contact obtained by RT processing.

Delineation of Defects Reducing Schottky Barrier Heights on 4H-SiC by the Electrochemical Deposition

2008 ◽  
Vol 600-603 ◽  
pp. 373-376
Author(s):  
Masashi Kato ◽  
Kazuya Ogawa ◽  
Masaya Ichimura
Keyword(s):  
Schottky Barrier ◽  
Barrier Height ◽  
Electrochemical Deposition ◽  
Schottky Barrier Height ◽  
Proper Time ◽  
Etch Pits ◽  
Barrier Heights ◽  
Etch Pit ◽  
Deposition Voltage ◽  
Deposited Films

We identified regions with low Schottky barrier height on 4H-SiC surfaces by the electrochemical deposition of ZnO. When we adopt an appropriate deposition voltage, ZnO grew preferentially at the regions with the low Schottky barrier height. Thus, we were able to identify the ZnO film only at these regions if we stopped the deposition at a proper time. We compared positions of the deposited film and etch pit after molten NaOH etching. As a result, in a bulk 4H-SiC, the films were deposited around some of micropipe positions. On the other hand, in an epitaxial 4H-SiC layer, although approximately a half of deposited films seemed to grow at the etch-pit defect positions, other deposited films were grown at positions without etch-pit defects. Therefore the Schottky barrier heights were reduced by not only defects emerging as etch pits but also other kind of origins in epitaxial 4H-SiC.

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