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We propose an approach for in-situ real-time measuring the optical and electric properties of a thin film in parallel during the process of growth. The method is developed based on two techniques: differential reflectance spectroscopy (DRS) and field effect transistor (FET) structure based electrical characteristics testing method. In order to demonstrate the performance of the method, FETs with a bottom-gate structure are manufactured and the pentacene organic thin film is deposited by vacuum thermal evaporation as a transport layer on the top of the transistor, i.e. the insulator substrate of SiO2. The optical and electrical properties of the organic thin film are in-situ investigated during its growth. As obtained from the optical spectra, the DRS signal moves up and down along the wavelength. Its fluctuation amplitude increases quickly and is very sensitive to the variation of the thickness of the top most film since the shutter of the molecular evaporation source is open. A good agreement between the experimental data and the computational results with a four-layer structure model of Si/SiO2/pentacene/air suggests that the DRS signal here is mainly due to the interference that exists in the multilayer interfaces. In addition, there are two characteristic peaks at 629 nm (1.97 eV) and 673 nm (1.84 eV) appearing occurs clearly in the DRS spectra at the initial stage of the growth. It means that the pentacene layer forms a thin film phase structure. Furthermore, the growth rate is evaluated to be 0.23 nm/min. When the effective thickness of the pentacene layer reaches 28 nm, calculated from the growth rate and the measured time, the conductivity of the organic FET becomes noticeable. It implies that an electrical conducting layer is already formed. After that, the thickness of the conducting layer continuously increases, while the current between the drain and the source increases slowly and turns to be saturated. After a 15-hour film growth, the sample has a threshold voltage of -20 V and the charge carrier mobility is 3.1×10-3 cm2/(V· s). These data confirm that the sample is an FET although its electronic properties are not good enough. These results show that the proposed approach is a useful measurement tool to build the relationships among the data of the optical spectrum, the electrical property, and the structure of the thin films. Hence, it is valuable for both the explanation of the growth mechanism of the thin film in research and the optimization of its preparation process in industry.
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Keywords:
- organic semiconductor thin film /
- optical and electrical properties /
- in-situ measurement /
- pentacene
[1] Podzorov V, Pudalov V M, Gershenson M E 2003 Appl. Phys. Lett. 82 1739
[2] Crone B, Dodabalapur A, Lin Y Y, Filas R W, Bao Z, LaDuca A, Sarpeshkar R, Katz H E, Li W 2000 Nature 403 521
[3] Drury C J, Mutsaers C M J, Hart C M, Matters M, Leeuw D M 1998 Appl. Phys. Lett. 73 108
[4] Yu P Y, Cardona M 1996 Semiconductor Science and Technology (Berlin: Springer Verlag) pp103-110
[5] Karl N 2003 Synth. Met. 13 133
[6] Wu S K, Wang P F 2009 Introduction to organic electronics (Beijing: Chemical Industry Press) pp5-6 (in Chinese) [吴世康, 汪鹏飞 2009 有机电子学概论 (北京: 化学工业出版社) 第 5–6 页]
[7] Yan D H, Wang H P, Du B X 2008 Introduction to organic semiconductor heterojunction (Beijing: Science Press) pp88-95 (in Chinese) [闫东航, 王海波, 杜宝勋 2008 有机半导体异质结导论(北京: 科学出版社)第 88–95 页]
[8] Hu W P 2011 Organic Field Effect Transistor (Beijing: Science Press) pp181-188 (in Chinese) [胡文平 2011 有机场效应晶体管(北京: 科学出版社)第 181–188 页]
[9] Li H Q, Yu J S, Huang W, Shi W, Huang J 2014 Chin. Phys. B 23 038505
[10] Shehu A, Quiroga S D, D'Angelo P, Albonetti C, Borgatti F, Murgia M, Scorzoni A, Stoliar P, Biscarini F 2010 Phy. Rev. Lett. 104 246602
[11] Jiang L, Dong H L, Meng Q, Li H X, He M, Wei Z M, He Y D, Hu W P 2011 Adv. Mater. 23 2059
[12] J. H. Schon, Ch. Kloc 2001 Appl. Phys. Lett. 78 3538
[13] S. P. Park, S. S. Kim 2002 Appl. Phys. Lett. 80 2872
[14] Arian Shehu, Santiago D. Quiroga, Pasquale D'Angelo, Cristiano Albonetti, Francesco Borgatti, Mauro Murgia, Andrea Scorzoni, Pablo Stoliar, Fabio Biscarini 2010 Phys. Rev. Lett. 104 246602
[15] Yang D, Zhang L, Yang S Y, Zou B S 2015 Acta Phys. Sin. 64 108503 (in Chinese) [杨丹, 张丽, 杨盛谊, 邹炳锁 2015 64 108503]
[16] Reese C, Bao Z N 2007 Mater. Today 10 20
[17] Zhang D, Zhao K, Deng J C 2012 J. Optoelectronics. Laser 23 2273 (in Chinese) [张达, 赵恺, 邓家春 2012 光电子. 激光 23 2273]
[18] Forker R, Gruenewald M, Fritz T 2012 Annual Reports Section C (Physical Chemistry) 108 34
[19] Zhang L 2014 Ph. D. Dissertation (Tianjin: Tianjin University) (in Chinese) [张雷 2014 博士学位论文 (天津: 天津大学)]
[20] Borenszten Y 2005 Phys. Stat. Sol. 202 1313
[21] Yao Y, Hu C G, Xu Z Y, Zhang L, Fu X, Hu X T 2015 Spectrosc. Spect. Anal. 35 1320 (in Chinese) [姚姚, 胡春光, 徐臻圆, 张雷, 傅星, 胡小唐 2015 光谱学与光谱分析 35 1320]
[22] Philipp H R 1998 Handbook of Optical Constants of Solids (Vol. 1) (San Diego: Academic Press) pp719-763
[23] Auslender M, Hava S 1998 Handbook of Optical Constants of Solids (Vol. 3) (San Diego: Academic Press) pp155-186
[24] Faltermeier D, Gompf B, Dressel M, Tripathi A K, Pflaum J 2006 Phy. Rev. B 74 125416
[25] Sun Q J, Xu Z, Zhao S L, Zhang F J, Gao L Y 2011 Chin. Phys. B 20 017306
[26] Qi Q, Yu A F, Jiang P, Jiang C 2009 Appl. Surf. Sci. 255 5096
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[1] Podzorov V, Pudalov V M, Gershenson M E 2003 Appl. Phys. Lett. 82 1739
[2] Crone B, Dodabalapur A, Lin Y Y, Filas R W, Bao Z, LaDuca A, Sarpeshkar R, Katz H E, Li W 2000 Nature 403 521
[3] Drury C J, Mutsaers C M J, Hart C M, Matters M, Leeuw D M 1998 Appl. Phys. Lett. 73 108
[4] Yu P Y, Cardona M 1996 Semiconductor Science and Technology (Berlin: Springer Verlag) pp103-110
[5] Karl N 2003 Synth. Met. 13 133
[6] Wu S K, Wang P F 2009 Introduction to organic electronics (Beijing: Chemical Industry Press) pp5-6 (in Chinese) [吴世康, 汪鹏飞 2009 有机电子学概论 (北京: 化学工业出版社) 第 5–6 页]
[7] Yan D H, Wang H P, Du B X 2008 Introduction to organic semiconductor heterojunction (Beijing: Science Press) pp88-95 (in Chinese) [闫东航, 王海波, 杜宝勋 2008 有机半导体异质结导论(北京: 科学出版社)第 88–95 页]
[8] Hu W P 2011 Organic Field Effect Transistor (Beijing: Science Press) pp181-188 (in Chinese) [胡文平 2011 有机场效应晶体管(北京: 科学出版社)第 181–188 页]
[9] Li H Q, Yu J S, Huang W, Shi W, Huang J 2014 Chin. Phys. B 23 038505
[10] Shehu A, Quiroga S D, D'Angelo P, Albonetti C, Borgatti F, Murgia M, Scorzoni A, Stoliar P, Biscarini F 2010 Phy. Rev. Lett. 104 246602
[11] Jiang L, Dong H L, Meng Q, Li H X, He M, Wei Z M, He Y D, Hu W P 2011 Adv. Mater. 23 2059
[12] J. H. Schon, Ch. Kloc 2001 Appl. Phys. Lett. 78 3538
[13] S. P. Park, S. S. Kim 2002 Appl. Phys. Lett. 80 2872
[14] Arian Shehu, Santiago D. Quiroga, Pasquale D'Angelo, Cristiano Albonetti, Francesco Borgatti, Mauro Murgia, Andrea Scorzoni, Pablo Stoliar, Fabio Biscarini 2010 Phys. Rev. Lett. 104 246602
[15] Yang D, Zhang L, Yang S Y, Zou B S 2015 Acta Phys. Sin. 64 108503 (in Chinese) [杨丹, 张丽, 杨盛谊, 邹炳锁 2015 64 108503]
[16] Reese C, Bao Z N 2007 Mater. Today 10 20
[17] Zhang D, Zhao K, Deng J C 2012 J. Optoelectronics. Laser 23 2273 (in Chinese) [张达, 赵恺, 邓家春 2012 光电子. 激光 23 2273]
[18] Forker R, Gruenewald M, Fritz T 2012 Annual Reports Section C (Physical Chemistry) 108 34
[19] Zhang L 2014 Ph. D. Dissertation (Tianjin: Tianjin University) (in Chinese) [张雷 2014 博士学位论文 (天津: 天津大学)]
[20] Borenszten Y 2005 Phys. Stat. Sol. 202 1313
[21] Yao Y, Hu C G, Xu Z Y, Zhang L, Fu X, Hu X T 2015 Spectrosc. Spect. Anal. 35 1320 (in Chinese) [姚姚, 胡春光, 徐臻圆, 张雷, 傅星, 胡小唐 2015 光谱学与光谱分析 35 1320]
[22] Philipp H R 1998 Handbook of Optical Constants of Solids (Vol. 1) (San Diego: Academic Press) pp719-763
[23] Auslender M, Hava S 1998 Handbook of Optical Constants of Solids (Vol. 3) (San Diego: Academic Press) pp155-186
[24] Faltermeier D, Gompf B, Dressel M, Tripathi A K, Pflaum J 2006 Phy. Rev. B 74 125416
[25] Sun Q J, Xu Z, Zhao S L, Zhang F J, Gao L Y 2011 Chin. Phys. B 20 017306
[26] Qi Q, Yu A F, Jiang P, Jiang C 2009 Appl. Surf. Sci. 255 5096
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