International Journal of Energetica (IJECA) https://www.ijeca.info ISSN: 2543-3717 Volume 5. Issue 1. 2020 Page 31-36 . http://dx.doi.org/10.47238/ijeca.v5i1.120. June 2020 Page 31 Extraction of the electrical parameters of the Au/InSb/InP Schottky diode in the temperature range (300 K- 425 K) Ali Sadoun 1 , Imad Kemerchou 2,3 1 Applied Microelectronics Laboratory, Djillali Liables University of Sidi Bel Abbes, ALGERIA 2Laboratory of Analysis and Control of Energy Systems and Networks, University Thelidji Amar of Laghouat, ALGERIA 3Materials Science and Engineering Program, State University of New York at Binghamton, Binghamton, New York 13902, USA E-mail: 3ali39@gmail.com Abstract – In this work, we have presented a theoretical study of Au/InSb/InP Schottky diode based on current-voltage (I-V) measurement in the temperature range ( 300 K- 425 K). Electrical parameters of Au/InSb/InP such as barrier height (Φb), ideality factor and series resistance have been calculated by employing the conventional (I-V), Norde, Cheung and Chattopadhyay methods. Measurements show that the Schottky barrier height (SBH), ideality factor and series resistance, RS for Au/InSb/InP Schottky diode in the temperature range (300 K–425 K) are 0.602-0.69eV, 1.683-1.234 and 84.54-18.95 (Ω), respectively. These parameters were extracted using Atlas- Silvaco-Tcad logical. Keywords: Cheung and Chattopadhyay methods, Schottky barrier, Schottky diode, SBH, Silvaco. Received: 09/04/2020 – Accepted: 20/06/2020 I.1. Introduction Semiconductors of the (III-V) family have important applications in the field of electronics and optoelectronics. Recently, (III-V) semiconductors have received a great deal of attention for the fabrication of microwave devices as well as integrated circuits used in modern high-speed optical communication systems [1-4]. Among the most widely used III-V compounds are GaN, GaAs, GaP, and InP, because of their band gap to their wide band gaps, stability at high temperatures, electron mobility, hardness, low iconicity and high terminal conductivity [4-8]. InP binary compound belongs to a family of III-V semiconductors which is widely used in the manufacture of electronic components such as Schottky diode (MS), metal-isolate-semiconductor (MIS) structure, MOS, transistor,….etc [9-12]. InP binary compound is a direct band gap semiconductor with Eg = 1.423 eV and lattice parameter a= 5.869 at 300 K [6]. This binary is a promising material for detectors in the long-wavelength spectral region, light emitters, solar cell application, and microwave field-effect transistors [2, 13- 16]. On the other hand, The InP binary compound has received a great deal of attention for the fabrication of Schottky diodes (Metal- InP). A study have investigated the forward bias current-voltage ( I - V) characteristics of Au/n-InP Schottky barrier diodes (SBDs) in the temperature range of 160-400 K but by using Atlas device simulator of the software Silvaco-Tcad, have simulated the (I–V) and (C–V) characteristics of the Au/n-InP Schottky as a function of the temperature range 200–400 K [17,18]. More recently work have analyzed the microstructural, chemical and elemental composition properties of CuO/n-InP junction using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy (EDAX) techniques [19]. Another experience have prepared Graphite/InP Schottky diode and analyzed their electrical characterization, using (I–V–T) and (C–V) methods [20,21]. This work aims to present the current-voltage (I– V) measurement for Au/InSb/InP Schottky diodes in the temperature range (300 K- 425 K). The surface of the InP is restructured by an InSb’s thin film of several monolayers. Electrical characteristics of Au/InSb/InP Schottky diodes, such as ideality factor (n), barrier height, and series resistance (Rs) were investigated using (I-V), Norde, Cheung and Chattopadhyay methods. mailto:3ali39@gmail.com Ali Sadoun et al IJECA-ISSN: 2543-3717. June 2020 Page 32 MATERIAL AND METHOD II. 1. Current-voltage (I-V) method The effect of the diode resistor can be modeled by a series combination of a diode and a resistor (Rs) through which the current flows. In addition, in the case, the ideal diode the value of the ideality factor equals 1 while for the no ideal diode the value is superior to 1 (n >1 ). In the case of the Schottky diode, assuming that the current is due to a thermionic emission (TE), the relation between the applied forward bias and the current can be given by [22-25]. ……...…(1) (1) Here, ,n, k, and T present the reverse saturation current, the ideality factor, the Boltzmann constant, the absolute temperature in Kelvin, respectively. For the applied forward voltage (V > 3kT/q), the equation (1) can be written as [22-25]: …………………………………...(2) We could find the value of ( I0) by the plot ln (I) versus (v) at v = 0 volts. Then, by replacing the calculated (I0) value in the equation (2), we could find the Schottky barrier height (Φb). The ideality factor value can be extracted from the linear region of (ln (I) -v) curve (the straight line of the curve). ………………...……….(3) (3) where A is the rectifier contact area, (Φb) is the Schottky barrier height, The value of (Φb) can be deducted directly from I–V curves if the effective Richardson constant is known [22]. is the Richardson constant ( =9.4 A/cm 2 K 2 for n-InP [26]). The voltage (v) across the diode can then be expressed in terms of the total voltage drop v across the series combination of the diode and resistor. The value of n for an ideal diode is e is equal to one. High values of n can be attributed to the presence of the interfacial thin layer and a wide distribution of low-Schottky barrier height patches (or barrier inhomogeneities) [27]. It can also be described and expression of the voltage (v) across the diode can then out of the total voltage drop (v) across the series combination of the diode and resistor, out of which the current flows, It can be composed or formed the effect of the diode resistance can be modeled with a series combination of a diode and a resistor Rs [27]. II. 2. Cheung method the Schottky barrier height (Φb), the ideality factor , and the series resistance (Rs) can be calculated from a second method called Cheung and Cheung [28]. In this method, the series resistance (Rs) and the ideality factor are determined by the following functions [28]: ………………..…...(4) also, Schottky barrier height can be defined by Cheung’s relation [28]: …....(5) II. 3. Norde method Alternatively, another method called Norde approximation [29] can be used to calculate the two parameters that are the series resistance and the barrier height of Au/InSb/InP structure. The Norde approximation is defined as [29]: ……….……….. ………..…(6) Here, is an integer (dimensionless) greater than n (n=1.84), and I (V) present the current which is acquired from the (I–V) curve. In this approximation, Φb and Rs values can be determinate by using the following relations [29, 30]: ……………..………………..(7) Rs = - ………………………………………..(8) where value is obtained from the ln I-V curve, is the minimum point of the plot, (V) is the corresponding voltage and is present the current corresponding to (V0) in the I–V characteristic.[31] II. 4. Chattopadhyay model In addition, Chattopadhyay model can be also used to determine the ideality factor and barrier height values of the Schottky diode. In the present model, the barrier height Φb can be written as [32]: …….……..(9) Ali Sadoun et al IJECA-ISSN: 2543-3717. June 2020 Page 33 Where, present the critical surface potential, is the critical voltage, is the potential difference between the Fermi level and bottom of the conduction band, and (C2) present the parameter inverse of the diode ideality factor[31]. The critical surface potential value ( ) can be determined by the following relation [32, 33]: ……………………………...(10) (10) And Parameter can be calculated from the following relation: )11(....................................................... (11) Here, and are the effective conduction band density of states and the carrier concentration, respectively. Using relation (9), we have calculated for different temperatures (300K, 325K, 375K, and 425K). Theirs obtained values are 0.04eV, 0.044 eV, 0.0512 eV, and 0.581eV, respectively. In order to determinate the inverse of the ideality factor ( ), we have used the following relation [32]: …………………………………….......(12) III. Result and discussions III.1. Results of current-voltage (I-V method) Figure 1 shows our simulated current-voltage (I-V) characteristics of Au/InSb/InP Schottky diode, using Atlas-Silvaco-Tcad soft word, at some selected temperature (300,325,375and 425 K). From Figure 1, (I– V) characteristics plot show that the Au/InSb/InP structure has a Schottky diode behavior. In addition, we remarked that all curves have similar behaviors with a qualitative difference. In addition, we observed that there is a deviation of the current and voltage characteristics of the linear. This deviation can be due to the series resistance (Rs). Our obtained results of saturation current (I0), barrier height (Φb) and ideality factor are shown in Table 1. 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 -15 -14 -13 -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 Simul. 300 K 325 K 375 K 425 K L n (I )( A ) v(V) Figure .1. The (I–V) characteristics of Au/InSb/InP Schottky diode in the temperature range (300–425 K). III.2. Results of Cheung method Figure 2 shows the obtained of and H(I) as a function of ( I ) for Au/InSb/InP structure, at different temperatures(300, 325, 375, and 425K). 0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 Simul. I(A) d V /d ln (I ) (v ) (a) 0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Simul. T=425K T=375K T=325K T=300K T=425K T=375K T=325K T=300K I(A) H (I ) (v ) (b) Figure.2. the obtained of and H (I) as a function of (I) for Au/InSb/InP Schottky diode, at different temperatures The curve is fitted to a straight line and using (4). Both parameters ideality factor and series resistance (Rs) have been extracted from the intercept and the slope of the line. We defined the function H (I) by replacing the value of and the characteristics (I- V) in equation (5). The plot of H (I) as a function of (I) at different temperatures is shown in Figure 2 b. According to the Cheung method, the two parameters the height of the Schottky barrier (Φb), and the series resistance (Rs) can be determined [31, 34]. Where (Φb) Ali Sadoun et al IJECA-ISSN: 2543-3717. June 2020 Page 34 value is given by (y-axis) intercept of H (I) and (Rs) value is given by the slope. The obtained results of (n, Rs and(Φb) are shown in Table 1. III.3. Results of Norde method (2) Figure 3 shows the variation of Norde’s function as a function of V obtained from forward bias current- voltage characteristics of the Au/InSb/InP structure. Our obtained results of barrier height (Φb) , series resistance (RS), and (V0) are shown in Table 1. From Figure 3 (a), our determinate values of and are 0.529 V and 0.24 V, respectively, at T=300K. 0.0 0.2 0.4 0.6 0.8 1.0 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.85 0.90 V0=0.24V F(V0)=0.529V T=300K Simul. F (V ) v(V) 0.0 0.2 0.4 0.6 0.8 1.0 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.85 0.90 Simul. T=325 T=375 T=425 F (V ) v(V) Figure.3. F (V) as a function of V obtained from forward bias current- voltage characteristics of the Au/InSb/InP Schottky diode (a) at T=300K and (b) for T=(325, 375 and 425K) III.4. Results of Chattopadhyay model Figure 4 shows the surface potential-forward voltage curves of Au/InSb/InP structure for different temperatures (300K, 325K, 375K, and 425K). From behavior shown in Fig.4, we remarked that the Ψs decreases with the increases of V and Ψs value increases with the temperature (T). As showed in Fig. 4a, the critical values of (Vc) and Ψs were extracted from the curve of Ψs and the slope indicated in (red dashed line). The obtained results of the critical values (Vc) and , and barrier height (Φb) using, Chattopadhyay model, are shown in Table 1. 0.0 0.2 0.4 0.6 0.8 1.0 0.28 0.30 0.32 0.34 0.36 0.38 0.40 0.42 0.44 0.46 0.48 0.50 0.52 Simul. (vc,Ys)=(0.256,0.362) v(V) T=300K (a) 0.0 0.2 0.4 0.6 0.8 1.0 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70 (b) Y s( v ) Simul. Y s( v ) v(V) T=325K T=375K T=425K Figure. 4. Surface potential-forward voltage curves of the Au/InSb/InP Schottky diode According to what we found, we observed that the increases in temperature are accompanied by the decreases in the ideality factor and increases in the barrier height for all methods. These phenomena are due to the no pure thermionic emission current (TE) in the device [35, 36]. Because the charge carriers have no enough energy to cross the high barrier height into those low temperatures, but current transport is provided by lower parts of barrier height [37]. and also, we have remarked that the (Rs) value decreases with increasing temperatures. This decreases can be due to the increase of the free carrier concentration at low temperatures [38] . Also, the obtained results of (RS), using the four different methods, are slightly different. This different in the values of RS, is due to the different regions of (I-V) characteristics where we have determinate this quantity. In the case of the (I-V) method, we have employed the non-linear region while for Cheung and Norde methods we have used the linear region [19, 27]. The differences in the barrier height values, obtained from these methods, maybe due to the extraction of data from different regions of the forward-bias (I-V) plot [19, 33,39], where the Cheung’s functions are only accomplished for the non-linear region of forward bias (I–V ) curve and the Norde’s function are executed for the whole forward bias region of the current-voltage curve of the diode [40]. Our obtained value of barrier height and ideality factor, for both methods ( Ψs –V) and (I-V) [33]. The obtained results of(Φb0), (n) and (RS) parameters for Au/InSb/InP Schottky diode via (I-V) method, Norde method, Cheung method, and Chattopadhyay model are summarized in Table 1. Ali Sadoun et al IJECA-ISSN: 2543-3717. June 2020 Page 35 Table .1. The obtained values of saturation current, barrier height, ideality factor, series resistance, surface potential (Ψs), and critical voltage for Au/InSb/InP Schottky diode in the temperature range (300 K–420 K) Temperature 300 K 325 K 375 K 425 K From (I- V) characteristics Saturation current 10-5(A) 2.6 0.112 0.365 1.01 Barrier height, (Φb) (eV) 0.602 0.611 0.674 0.690 Ideality factor, n 1.683 1.624 1.362 1.234 Series resistance, RS (Ω) 84.54 60.86 37.12 18.95 From Cheung’ s method ( d V/dln I) versus I Series resistance, RS (Ω) 68.25 45.18 38.31 19.32 Ideality factor, n 2.011 1.927 1.674 1.312 From Cheung’ s method H( I) versus I Series resistance, RS(Ω) 62.01 45.18 27.72 16.55 Barrier height (Φb) (eV) 0.492 0.510 0.566 0.594 From Norde’s method Barrier height (Φb)(eV) 0.626 0.623 0.681 0.692 Series resistance, RS (Ω) 646.1 633.8 315.2 206.1 F (V0) (V) 0.526 0.548 0.592 0.605 V0 (V) 0.240 0.210 0.230 0.220 From Chattopadhyay ’s method Barrier height, (Φb)(eV) 0.526 0.541 0.605 0.644 Ideality factor, n 1.660 1.542 1.422 1.247 surface potential Ψs (V) 0.362 0.391 0.424 0.463 the critical voltage (V) 0.256 0.211 0.237 0.226 IV. 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