University, Harbin, The 49th Research Institute of China Electronics Technology Group Corporation, Harbin,

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1 Key Engineering Materials Online: ISSN: , Vols , pp doi: / Trans Tech Publications, Switzerland Simulation research of the long-base silicon magnetic sensitive diode negative-resistance characteristics on the base of ATLAS Zhao Xiaofeng 1,2 a, Li Lei 1,b, Wang ping 1,2c,Wen Dianzhong 1,d and Li Gang 1 1 Key Laboratory of Electronics Engineering, College of Heilongjiang Province, Heilongjiang University, Harbin, The 49th Research Institute of China Electronics Technology Group Corporation, Harbin, a zxf80310@126.com, b lileidyhyx@yahoo.com.cn, c wangping_57@126.com, d wendianzhong@126.com (corresponding author) Keywords: long-base silicon magnetic sensitive diode; negative resistance characteristics; deep impurities; ATLAS. Abstract. According to the experimental results of the long-base silicon magnetic sensitive diode, this paper adopted ATLAS software to establish the two dimensional simulation model in order to research the negative resistance characteristics of the long-base silicon magnetic sensitive diode. Deep impurities were introduced into the long base to study the effect of the concentration and the distribution of deep impurities on the current-voltage characteristics of the long-base silicon magnetic sensitive diode. The simulation results showed that the deep impurity in the long base was the main factor that impacted on the negative resistance characteristics of the long-base silicon magnetic sensitive diode. Introduction In the 1970s, the germanium magnetic sensitive transistors which had forward and reverse magnetic sensitivities were fabricated by alloying sintering process. In 2003, the new type silicon magnetic sensitive transistors [1,2,3,4] which had the rectangle-bank cubic structure were made on a p-type <100> orientation high resistance single crystal silicon. The experimental results show that the new type silicon magnetic sensitive transistor has a higher relative magnetic sensitivity of the collector current, the maximum of which can reach 227%/T. This device has the negative resistance and oscillation characteristics [5]. The collector electrode and base electrode of the new type silicon magnetic sensitive transistor can be approximately regarded as a C-π-B long-base silicon magnetic sensitive diode which has the negative resistance characteristics [6]. And this phenomenon is one of the factors that give rise to the negative resistance and oscillation characteristics of the new type silicon magnetic sensitive transistor. Based on the negative resistance characteristics of the long-base silicon magnetic sensitive diode, this paper adopts ATLAS software to establish the simulation model of the long-base silicon magnetic sensitive diode. The effect of the concentration and the distribution of deep impurities on the negative resistance and magnetic characteristics of the long-base silicon magnetic sensitive diode is researched, which lays foundation for the further analysis of the negative resistance and oscillation characteristics of the novel silicon magnetic sensitive transistor. The basic structure of the long-base silicon magnetic sensitive diode Figure 1 shows the basic structure model of the long-base silicon magnetic sensitive diode, which consists of a p + region, an n + region, a long base region and a recombination region. This structure is fabricated on the surface of a p-type <100> orientation high resistance single crystal silicon, which is also a component of the new type silicon magnetic sensitive transistor. The length of the long-base region L, the length of the recombination region L 0, the distance between the recombination region and the opposite side d, and the width of the long-base silicon magnetic sensitive diode w are principal parameters of the basic structure of the long-base silicon magnetic sensitive diode. All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans Tech Publications, (# , Pennsylvania State University, University Park, USA-18/09/16,08:06:03)

2 466 Micro-Nano Technology XIV L L 0 d x p + i n + w Figure 1. Basic structure of the long base silicon magnetic sensitive diode The negative resistance characteristics of the long-base silicon magnetic sensitive diode The characteristics of the p + -i-n + long-base silicon magnetic sensitive diode were researched by using KEITHLEY 4500-SCS semiconductor characteristic testing system and the magnetic field generator. At room temperature, the continuous current source supplied power and the supplied current ranged from 0 to A, the step of which was A. I th D E C Currnet(A) B= 0T B= +0.1T B= +0.2T B= -0.2T I 0 A B Figure 2.Negaive-resistance characteristics of the p + -i-n + long base silicon magnetic sensitive diode Voltage(V) Figure 3.Magnetic characteristics of the p + -i-n + long base silicon magnetic sensitive diode Figure 2 shows the current-voltage characteristics of the p + -i-n + long-base silicon magnetic sensitive diode without the external magnetic field. The experimental results show that the p + -i-n + long-base silicon magnetic sensitive diode has the negative resistance characteristics. The negative resistance curves [7,8] can be divided into Line AB, Line BC, and Line DE. Line AB, Line BC and Line DE indicate the cutoff region, the negative resistance region, and the positive resistance region, respectively. The voltage and current at B point is referred to as the turning voltage and the turning current. The voltage and current at D point is referred to as the maintaining voltage and the maintaining current. The negative resistance characteristic curve of the p + -i-n + long-base silicon magnetic sensitive diode can be described by the following: (1) When the current increases from A point, the value of the current is small and the curve is flat. (2) If the current reaches B point, the voltage decreases altogether with the negative resistance characteristics of the current increasing rapidly. (3) The current continues to increase until it reaches the maintaining current. The positive resistance region appears where the voltage increases linearly with the current increasing. Figure 3 shows the magnetic characteristic curves of the long-base silicon magnetic sensitive diode. The turning voltage increases with the external forward magnetic field, and diminishes with the external reverse magnetic field.

Key Engineering Materials Vols. 562-565 467 The simulation model and results of the long-base silicon magnetic sensitive diode The long-base region without deep impurities The simulation model.

3 Key Engineering Materials Vols The simulation model and results of the long-base silicon magnetic sensitive diode The long-base region without deep impurities The simulation model. The two dimensional simulation model of the long-base silicon magnetic sensitive diode was established with the aid of ATLAS software in this paper as Figure 4(a) shown. The x-axis represented the length direction of the near-intrinsic base. The coordinate interval of the p + region, the near-intrinsic base region and the n + region along the x-axis was from 0 to 200 µm, from 200 to 320 µm, from 320 to 380 µm, respectively. The y-axis represented the spacing between the side with the recombination region and the opposite one. The impurity concentration of both the p + region and the n + region was equal to cm -3, and that of the long-base region was cm -3. On the basis of the simulation model, the recombination region was created on the surface of the long-base region and consisted of deep impurities. The coordinate interval of the recombination region was from 230 to 290 µm along the x-axis, from 0 to 50 nm along the y-axis. L 0 p + n + p + n + Conduction Band Hole Concentration Electron Concentration y Valence Band x (a) Figure 4.Simulation model and energy band diagram of the long base silicon magnetic sensitive diode (a )simulation model (b) energy band diagram (b) Figure 4(b) shows the energy band diagram, and the electron and hole concentration distributions of the long-base silicon magnetic sensitive diode under the zero bias. The simulation range in the x-axis is from 195 to 325 µm, and that in the y-axis is equal to 2 µm. If the long-base silicon magnetic sensitive diode is under the zero bias, the equilibrium pn junction is formed between the heavy doping region and the near-intrinsic region. The pn junction has the uniform Fermi level at equilibrium. Figure 4(b) shows the energy band diagram of the p + -i junction and n + -i junction formed between the heavy doping region and the near-intrinsic region. Figure 4(b) also shows that the hole and electron concentrations are compatible with the doping condition, namely the concentration of the heavy doping region is cm -3 and that of the near-intrinsic region is cm -3. The space charge region is formed near the p + -i junction and the n + -i junction. Because there is six-order of magnitude difference on concentration between the heavy doping region and the near-intrinsic region, the space charge region is largely in the near-intrinsic region. The current-voltage characteristics. Figure 5 shows the current-voltage characteristic curves of the simulation model at the external magnetic field of 0 T, ±0.5 T perpendicular to the xy planar. The simulation results show the current-voltage characteristics of the long-base silicon magnetic sensitive diode have no negative resistance characteristics, but have forward and reverse sensitivities.

468 Micro-Nano Technology XIV B=-0.5T B=0T B=0.5T Figure 5.

Deep impurities were introduced to the different ranges of the long base in this paper to study the effect of the deep impurity distribution on the negative resistance characteristics, and the effect

The distribution length of deep impurities L t was equal to 70 µm along the x-axis, and the coordinate interval of deep impurities was from 0 µm to 5 µm along the y-axis.

4 468 Micro-Nano Technology XIV B=-0.5T B=0T B=0.5T Figure 5.Simulation result of I-V characteristics of the long base silicon magnetic sensitive diode The long-base region with deep impurities The simulation model. Deep impurities were introduced to the different ranges of the long base in this paper to study the effect of the deep impurity distribution on the negative resistance characteristics, and the effect of the deep impurity concentration on the negative resistance characteristics with a certain deep impurity distribution. Deep impurities were introduced from the p + -i junction. The distribution length of deep impurities L t was equal to 70 µm along the x-axis, and the coordinate interval of deep impurities was from 0 µm to 5 µm along the y-axis. The concentration of deep impurities was equal to cm -3. The simulation range in the x-axis was from 195 to 325 µm, and that in the y-axis was equal to 2 µm. L 0 p + L t n + Conduction Band Hole Concentration Electron Concentration Valence Band y x (a) (b) Figure 6.Simulation model and energy band diagram of the long base silicon magnetic sensitive diode (a )simulation model (b) energy band diagram Figure 6(a) shows the simulation model with deep impurities in the long base. Figure 6(b) shows the energy band diagram, and electron and hole concentration distributions of the long-base silicon magnetic sensitive diode under the zero bias. The hole and electron concentrations in the heavy doping region are compatible with the doping condition as Figure 6(b) shown. Nevertheless, the concentration of the shallow p-type concentration is cm -3, and the hole concentration with deep impurities in the long base is lower than the one without deep impurities. The relative electron concentration increases due to n 0 p 0 =n i 2 at equilibrium. The energy level with deep impurities in the long base is slightly lower than the one without deep impurities in the long base. The effect of the deep impurity distribution on the negative resistance characteristics. Deep impurities were introduced from the p + -i junction. The distribution length L t along the x-axis was 60 µm, 70µm, 80µm and 90µm, respectively. Moreover, the coordinate range along the y-axis was from 0 to 5 µm. The deep impurity concentration was cm -3. The simulation results are shown

Key Engineering Materials Vols. 562-565 469 as Figure 7. When L t is equal to zero, there is no negative resistance characteristic.

5 Key Engineering Materials Vols as Figure 7. When L t is equal to zero, there is no negative resistance characteristic. However, there are negative resistance characteristics with deep impurities in the long base. When the length L t of deep impurities along the x-axis increases from 60 µm to 90 µm, the relative turning voltage and maintaining voltage in the negative resistance characteristic curves wane cm -3 Lt=0µm cm cm cm cm -3 Lt=90µm Lt=70µm Lt=60µm Lt=80µm Figure 7.Simulation result of I-V characteristics of the long base silicon magnetic sensitive diode Figure 8.Simulation result of I-V characteristics of the long base silicon magnetic sensitive diode The effect of the deep impurity concentration on the negative resistance characteristics. Deep impurities were introduced into the base of the simulation model and started from the p + -i junction. The coordinate interval of deep impurities was from 0 to 5µm along the y-axis, and L t was equal to 70 µm. Figure 8 shows the effect of the deep impurity concentration which is cm -3, cm -3, cm -3, cm -3, cm -3, respectively, on the negative resistance characteristics. The simulation results show when the deep impurity concentration shifts from to cm -3, the turning voltage and maintaining voltage increase in the negative resistance characteristic curves. The magnetic sensitive characteristics of the long-base silicon magnetic sensitive diode. Based on the simulation model, deep impurities were introduced into the base, the coordinate interval of which was from 0 to 5µm along the y-axis, and L t was equal to 70 µm. The deep impurity concentration was equal to cm -3. B=-0.5T B=0T B=0.5T Figure 9.Simulation result of the long base silicon magnetic sensitive diode characteristics Figure 9 shows the current-voltage characteristic curves at the external magnetic filed of 0T, ±0.5T perpendicular to the xy planar. The simulation results show that the silicon magnetic sensitive diode has forward and reverse sensitivities with deep impurities on the surface of the near-intrinsic base. Furthermore, the bias voltage at the magnetic field B=0T is less than the one at the magnetic field B=0.5T and more than the one at the magnetic field B=-0.5T.

6 470 Micro-Nano Technology XIV Conclusion This paper adopts KEITHLEY 4500-SCS semiconductor characteristic testing system and the magnetic field generator to research the negative resistance characteristics of the long-base silicon magnetic sensitive diode. In terms of it, the simulation model of the long-base silicon magnetic sensitive diode is established by ATLAS software. The effect of the distribution and the concentration of deep impurities on the negative resistance characteristics of the long-base silicon magnetic sensitive diode is researched by introducing deep impurities into the long base. The simulation results show that the negative resistance characteristic appears when deep impurities are introduced into the long base of the long-base silicon magnetic sensitive diode. And the distribution and the concentration of deep impurities impact on the turning voltage and the maintaining voltage of the negative resistance characteristics. The results indicate that the negative resistance characteristics of the long-base silicon magnetic sensitive diode are largely dependent on the deep impurity in the long base. The experiment and simulation results lay the foundation for the further analysis of the negative resistance characteristics of the long-base silicon magnetic sensitive diode. Acknowledgements This work is supported by the National Natural Science Foundation of China ( ) and Foundation for University Young Key Teacher of Heilongjiang Province (1251G046) and Excellent Youth Foundation of Heilongjiang University(JCL201007). References [1] Zhao Xiaofeng, Wen Dianzhong, Fabrication technology research of new type silicon magnetic-sensitive transistor, J. Rare Metal Materials and Engineering. 35 (2006) [2] Wen Dianzhong, Study on laser etching emitter region-groove approach of magnetic-sensitive silicon transistor, J. Chinese Journal of Lasers. 30 (2003) [3] Wen Dianzhong, Mu Changsheng, Zhao Xiaofeng, Adopt MEMS Techniques Make Magnetic Sensitive Silicon Transistor, J. Journal of Transducer Technology. 20 (2001) [4] S.M. Sze, Modern semiconductor device physics, M.John Wiley & Sons. Inc. 1998, [5] Zhao Xiaofeng, Wen Dianzhong, Negative-resistance oscillations characteristics of a new type Silicon magnetic sensitive transistor on MEMS, J. Chinese Journal of Semiconductors. 26(2005) [6] Wen Dianzhong, Negative-resistance characteristics studies in silicon double injection p + πn + magnetic-device. International Society for Optical Egineering. (2001) [7] Guo Weilian, Li Xiaoyun, Niu Pingjuan, et al. The characteristics and simulation of photobidirectional negative resistance transistor (PBNRT), Solid-State and Integrated-Circuit Technology. 3 (2004) [8] TSAY-JIU, SHIEH, Computer analysis of the negative differential resistance switching phenomenon of double-injection devices, J. Electron Devices. 36 (1989)

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