Indium antisite defect In P-related photoluminescence has been observed in Fe-diffused semi-insulating (SI) InP. Compared to annealed undoped or Fe-predoped SI InP, there are fewer defects in SI InP obtained by long-duration, high-temperature Fe diffusion. The suppression of the formation of point defects in Fe-diffused SI InP can be explained in terms of the complete occupation by Fe at indium vacancy. The In P defect is enhanced by the indium interstitial that is caused by the kick out of In and the substitution at the indium site of Fe in the diffusion process. Through these Fe-diffusion results, the nature of the defects in annealed undoped SI InP is better understood. © 2002 American Institute of Physics.published_or_final_versio

Chen, YH

Dong, HW

Fung, S

Jiao, JH

Lin, LY

Zhang, YH

Zhao, JQ

Zhao, YW

Applied Physics Letters

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Title Creation and suppression of point defects through a kick-outsubstitution process of Fe in InPAuthor(s) Zhao, YW; Dong, HW; Chen, YH; Zhang, YH; Jiao, JH; Zhao, JQ;Lin, LY; Fung, SCitation Applied Physics Letters, 2002, v. 80 n. 16, p. 2878-2879Issued Date 2002URL http://hdl.handle.net/10722/42466Rights Creative Commons: Attribution 3.0 Hong Kong LicenseAPPLIED PHYSICS LETTERS VOLUME 80, NUMBER 16 22 APRIL 2002Creation and suppression of point defects through a kick-out substitutionprocess of Fe in InPY. W. Zhao,a) H. W. Dong, Y. H. Chen, Y. H. Zhang, J. H. Jiao, J. Q. Zhao, and L. Y. LinMaterials Science Centre, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912,Beijing 100083, People’s Republic of ChinaS. FungDepartment of Physics, The University of Hong Kong, Hong Kong, People’s Republic of China~Received 31 January 2002; accepted for publication 6 March 2002!Indium antisite defect InP-related photoluminescence has been observed in Fe-diffusedsemi-insulating ~SI! InP. Compared to annealed undoped or Fe-predoped SI InP, there are fewerdefects in SI InP obtained by long-duration, high-temperature Fe diffusion. The suppression of theformation of point defects in Fe-diffused SI InP can be explained in terms of the completeoccupation by Fe at indium vacancy. The InP defect is enhanced by the indium interstitial that iscaused by the kick out of In and the substitution at the indium site of Fe in the diffusion process.Through these Fe-diffusion results, the nature of the defects in annealed undoped SI InP is betterunderstood. © 2002 American Institute of Physics. @DOI: 10.1063/1.1473695#Impurity diffusion in semiconductors has been studiedextensively in the past. In III–V compounds, the mechanismof atomic diffusion is well understood.1 Fast impurity diffus-ers, such as Zn and Fe, usually diffuse via the kick-out sub-stitution mechanism in GaAs and InP.2–5 In impurity diffusedInP, defects such as indium precipitate, interstitial-type dis-location loops have been detected.6 Most of these studies ondiffusion involve the comparison of the impurity profile withthe fitting to the proposed model in which the influence ofvacancy has been considered.3–5 However, the influence ofimpurity diffusion on the formation of point defects in dif-fused InP has rarely been reported.In this letter, we present photoluminescence ~PL! andphotoinduced transient current spectroscopy ~PITCS! resultsof semi-insulating ~SI! InP obtained by high-temperature Fediffusion. By comparing with the results of annealed un-doped SI InP, it is found that a number of defects have beensuppressed and an indium antisite InP defect is formed inFe-diffused SI InP.The samples used in the experiment were prepared byannealing n-type undoped InP wafers grown by the liquid-encapsulated Czochralski ~LEC! method. The electron con-centration of as-grown LEC undoped InP was (3 – 6)31015 cm23. The annealing was carried out in a sealedquartz tube at 930 °C for 80 h. A quantity of 5N Fe powderand 6N red phosphorus at a mole ratio of 1:2 were charged inthe quartz tube before annealing. In this way, FeP2 withmoderate vapor pressure can be formed at the annealingtemperature7,8 and Fe diffusion was thus realized. After an-nealing, the wafers were cooled at 40 °C/h to room tempera-ture. This process is found to convert the undoped n-typeLEC InP to a SI material with resistivity and mobility above107 V cm and 3000 cm2/V s, respectively. The SI InP waferso formed exhibits a good profile and radial uniformity.9 Thistechnique has proved to be a promising method for thea!Electronic mail: zhaoyw@red.semi.ac.cn2870003-6951/2002/80(16)/2878/2/$19.00Downloaded 06 Nov 2006 to 147.8.21.97. Redistribution subject to preparation of high-quality SI substrates. It should be men-tioned that undoped LEC InP with a carrier concentration ofabout 331015 cm23 can also be annealed into SI materialunder similar conditions, the only difference being the ambi-ance in the quartz tube is pure phosphorus. For PL andPITCS measurements, 0.6-mm-thick samples polished onone side were used. A layer of more than 60 mm of the SI InPwafer was removed during the lapping and polishing process.The PITCS system is a homemade setup with a conven-tional configuration. The PL system is a Bruck commercialISF120 instrument equipped with an argon-ion laser and agermanium detector and the laser excitation power is 30 mW.PL spectra of Fe-diffused and undoped SI InP are shownin Fig. 1. A noticeable difference of the spectra is that abroad peak centered at 1.3 eV can be observed in the Fe-diffused sample. The spectra of as-grown undoped n-type,Fe-doped and undoped SI InP are basically the same. Sincethe 1.3 eV peak is only detected in Fe-diffused SI InP, it isreasonable to assume that this PL feature is associated withFIG. 1. Photoluminescence spectra at 10 K of Fe-diffused SI InP ~solid line!and undoped SI InP ~dashed line!.8 © 2002 American Institute of PhysicsAIP license or copyright, see http://apl.aip.org/apl/copyright.jsp2879Appl. Phys. Lett., Vol. 80, No. 16, 22 April 2002 Zhao et al.Fe diffusion in the annealing process. A 1.3 eV PL peak wasalso detected in electron-irradiated undoped and Fe-dopedInP in the past.10–12 Experimental results have shown thatthis structure is due to the electron transition from the con-duction band to the second ionized level of the indium anti-site InP acceptor defect in InP.10,12 A PL peak at 1.393 eV,which corresponds to the transition of a conduction-bandelectron to the first ionized level of InP,12 can also be seen inthe spectrum. Thus, our result seems to imply that indiumantisite defect InP has been formed in Fe-diffused SI InP.PITCS results of the Fe-diffused and undoped SI InPsample are shown in Fig. 2. Once again, an obvious differ-ence can be seen between the two samples. Only two defectsaround 0.20 and 0.64 eV have been observed in Fe-diffusedSI InP. This is in great contrast to the five defects detected inthe undoped SI InP material located at 0.22, 0.25, 0.37, 0.51,and 0.63 eV. Our results of defects in undoped SI InP aresimilar to those of Marrakchi et al.13 and Fang et al.14 It hasalso been found that the quantity and signature of defects inundoped SI InP are the same as those in SI InP prepared byannealing n-type InP predoped with a low concentration ofFe.13,15 Based on this analysis, it can be concluded that Fediffusion has suppressed the formation of three defects in theSI InP material. It is interesting to note that nondiffusion Fedoping in InP does not produce such an effect, again indicat-ing a correlation between Fe diffusion and defect suppres-sion. As seen in Fig. 2, the Fe acceptor-related 0.64 eV peakin Fe-diffused SI InP is much stronger. This fact suggeststhat Fe has substituted indium and acted as an effective deepcompensation center in Fe-diffused SI InP.A well-established difference between Fe diffusion andordinary doping in InP is that the Fe impurity incorporatedby doping during LEC growth in the latter process has al-ready occupied an indium site before any subsequent anneal-ing treatment. From our observation here, the formation ofInP and the suppression of three defects in Fe-diffused SI InPseem most likely to be related to the diffusion mechanism. Amodel is invoked here to explain this observed phenomenon.The mechanism of Fe diffusion in InP is believed to be akick-out substitution process.2 Since Fe normally substitutesindium in InP, an indium interstitial will be created when aFIG. 2. Photoinduced transient current spectra of Fe-diffused SI InP ~a! andundoped SI InP ~b!. Curves have been moved for better clarity.Downloaded 06 Nov 2006 to 147.8.21.97. Redistribution subject to Fe diffuses in the material. During the subsequent high-temperature annealing process, the interstitial indium atommay have a strong tendency to occupy a phosphorus site,hence, forming an antisite defect in the Fe-diffused material.At the same time, as an additional effect, the substitutionaloccupation of Fe at the indium site means that indium-vacancy-related defects will also be greatly inhibited. A pre-vious study has shown that the formation of these defects inundoped SI InP has a close relationship with the indiumvacancy.16 Indeed, in as-grown InP a hydrogen vacancy com-plex can be detected.16,17 Experimental studies have con-firmed that this complex is annihilated in annealed InP andan indium vacancy is produced as a result.16,18 Such a pro-cess can explain why there are more thermally induced de-fects in annealed undoped and Fe predoped SI InP than thatin Fe-diffused SI InP. Our results also indicate that thesedefects are not impurity contamination related; otherwise,they cannot be suppressed by Fe diffusion. This interpreta-tion is proving to be very helpful for the understanding of thenature of defects in annealed undoped SI InP.The work described in this paper is partially supportedby a grant from the Research Grant Council of the HongKong Special Administrative Region, China ~under ProjectNo. HKU7137/99P!.1 B. Tuck, Atomic Diffusion in III–V Semiconductors ~Hilger, Bristol,1988!.2 H. Zimmermann, U. Go¨sele, and T. Y. Tan, Appl. Phys. Lett. 62, 75~1993!.3 M. R. Brozel, E. J. Foulkes, and B. Tuck, Phys. Status Solidi A 72, K159~1982!.4 H. B. Serreze and H. S. Marek, Appl. Phys. Lett. 49, 210 ~1986!.5 S. Yu, T. Y. Tan, and U. Go¨sele, J. Appl. Phys. 69, 3547 ~1991!.6 D. Wittorf, A. Rucki, W. Ja¨ger, R. H. Dixon, K. Urban, H. G. Hettwer, N.A. Stolwijk, and H. Mehrer, Appl. Phys. Lett. 77, 2843 ~1995!.7 D. Wolf, G. Hirt, and G. Mu¨ller, J. Electron. Mater. 24, 93 ~1995!.8 M. Uchida, T. Asahi, K. Kainosho, Y. Matsuda, and O. Oda, Jpn. J. Appl.Phys., Part 1 38, 985 ~1999!.9 Y. W. Zhao, H. W. Dong, J. H. Jiao, J. Q. Zhao, L. Y. Lin, N. F. Sun, andT. N. Sun, Chinese J. Semicond. 3, 285 ~2002!.10 F. P. Korshunov, S. I. Radautsan, N. A. Sobolev, I. M. Tiginyanu, V. V.Ursaki, and E. A. Kudryavtseva, Sov. Phys. Semicond. 23, 980 ~1989!.11 S. I. Radautsan, I. M. Tiginyanu, V. V. Ursaki, F. P. Korshunov, N. A.Sobolev, and E. A. Kudryavtseva, Solid State Commun. 7, 525 ~1993!.12 K. Kuriyama, K. Sakai, M. Okada, and K. Yokoyama, Phys. Rev. B 52,14578 ~1995!.13 G. Marrakchi, K. Cherkaoui, A. Karoui, G. Hirt, and G. Mu¨ller, J. Appl.Phys. 79, 6947 ~1996!.14 Z. Q. Fang, D. C. Look, M. Uchida, K. Kainosho, and O. Oda, J. Electron.Mater. 27, L68 ~1998!.15 R. Fornari, A. Zappettini, E. Gombia, R. Mosca, K. Cherkaoui, and G.Marrakchi, J. Appl. Phys. 81, 7064 ~1997!.16 Y. W. Zhao, X. L. Xu, M. Gong, S. Fung, C. D. Beling, X. D. Chen, N. F.Sun, T. N. Sun, X. B. Guo, and Y. Z. Sun, Appl. Phys. Lett. 72, 2126~1998!.17 R. Darwich, B. Pajot, B. Rose, D. Robin, B. Theys, R. Rahbi, C. Porte,and F. Gendron, Phys. Rev. B 48, 17776 ~1993!.18 C. P. Ewels, S. O¨ berg, R. Jones, B. Pajot, and P. R. Briddon, Semicond.Sci. Technol. 11, 502 ~1996!.AIP license or copyright, see http://apl.aip.org/apl/copyright.jsp

Creation and suppression of point defects through a kick-out substitution process of Fe in InP

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Creation and suppression of point defects through a kick-out substitution process of Fe in InP

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