In this work, Raman spectra of zinc sulfide, zinc selenide, and zinc telluride thin film semiconductors
deposited by the close-spaced vacuum sublimation technique were investigated. All of the films showed
longitudinal optical phonon mode replicas. Varying the substrate temperature results in small shifts of the
phonon frequencies in ZnSe and ZnTe, but not in ZnS thin films.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3510

Cheong, H.

Ivashchenko, Maksym Mykolaiovych

Klymov, Oleksii Volodymyrovych

Kolesnyk, Maksym Mykolaiovych

Kurbatov, Denys Ihorovych

Nam, D.

Opanasiuk, Anatolii Serhiiovych

Иващенко, Максим Николаевич

Климов, Алексей Владимирович

Климов, Олексій Володимирович

Колесник, Максим Миколайович

Колесник, Максим Николаевич

Курбатов, Денис Игоревич

Курбатов, Денис Ігорович

Опанасюк, Анатолий Сергеевич

Опанасюк, Анатолій Сергійович

Іващенко, Максим Миколайович

У цій роботі були досліджені спектри комбінаційного розсіювання в тонких напівпровідникових плівках сульфіду цинку, селеніду цинку і телуриду цинку, нанесених за допомогою методу вакуумної сублімації в квазізамкнутом об'ємі. Всі плівки показали поздовжні оптичні репліки фононної моди. Зміна температури підкладки в результаті призвела до невеликим зміщень фононних частот в ZnSe і ZnTe, але не в тонких плівок ZnS.
При цитуванні документа, використовуйте посилання http://essuir.sumdu.edu.ua/handle/123456789/29350В этой работе были исследованы спектры комбинационного рассеяния в тонких  полупроводниковых пленках сульфида цинка, селенида цинка и теллурида цинка, нанесенных с помощью метода вакуумной сублимации в квазизамкнутом обьеме. Все пленки показали продольные оптические реплики фононной моды. Изменение температуры подложки в результате привело к небольшим сдвигам фононных частот в ZnSe и ZnTe, но не в тонких пленок ZnS.
При цитировании документа, используйте ссылку http://essuir.sumdu.edu.ua/handle/123456789/29350In this work, Raman spectra of zinc sulfide, zinc selenide, and zinc telluride thin  film semiconductors deposited by  the  close-spaced vacuum sublimation technique were investigated. All of the films showed longitudinal optical phonon mode replicas. Varying the substrate temperature results in small shifts of the phonon frequencies in ZnSe and ZnTe, but not in ZnS thin films.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2935

H. Cheong

D. Nam

Klymov, Olexii Volodymyrovych

Electronic Sumy State University Institutional Repository

Raman investigation on ZnS, ZnSe, ZnTe thin films obtained by CSVS technique

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE NANOMATERIALS: APPLICATIONS AND PROPERTIES Vol. 1 No 3, 03TF21(3pp) (2012)   2304-1862/2012/1(3)03TF21(3) 03TF21-1  2012 Sumy State University Raman Investigation on ZnS, ZnSe, ZnTe Thin Films Obtained by CSVS Technique  H. Cheong1,*, D. Nam1, A.S. Opanasyuk2, M.M. Ivashchenko2, O.V. Klymov2,  D.I. Kurbatov2, M.M. Kolesnyk2  1 Sogang University, 35 Baekbeom-ro, Mapo-gu, Seoul 121-742, Korea 2 Sumy State University, 2, Rimsky-Korsakov Str., 40007, Sumy, Ukraine  (Received 17 July 2012; revised manuscript received 27 July 2012; published online14 August 2012)  In this work, Raman spectra of zinc sulfide, zinc selenide, and zinc telluride thin film semiconductors deposited by the close-spaced vacuum sublimation technique were investigated. All of the films showed longitudinal optical phonon mode replicas. Varying the substrate temperature results in small shifts of the phonon frequencies in ZnSe and ZnTe, but not in ZnS thin films.   Keywords: Zinc sulfide, Zinc selenide, Zinc telluride, Films, Replica, Phonon, Raman spectroscopy.   PACS numbers: 71.55.Gs, 68.55. – a                                                             * hcheong@sogang.ac.kr 1. INTRODUCTION  Among II-VI semiconductors, zinc sulfide (ZnS), zinc selenide (ZnSe), and zinc telluride (ZnTe) have drawn much attention from researchers for their unique prop-erties and potential for applications such as: a basis layer in light-emitting diodes, photodetectors, gas sen-sors, X-ray detectors, window (owing to its wide band gap: ZnS-3.7 eV; ZnSe-2.7 eV; ZnTe-2.3 eV) and absorp-tion layers in solar cells, etc. [1, 2]. To obtain II-VI semiconductor films, researchers use various methods such as: electro-deposition [3], high-frequency cathode deposition [4], laser impulse and thermal sublimation, hot-wall epitaxy [5], and close-spaced vacuum sublimation (CSVS) [6, 7]. The last method, owing to its unique physical and techno-logical features of evaporator, has a possibility of ob-taining high-quality stoichiometric films.  Raman spectroscopy is a powerful tool to investigate the characteristics of semiconductors. However, not many studies have been done to compare zinc blende materials under various depositing conditions. In the present work, Raman spectroscopic investigation of ZnS, ZnSe, and ZnTe films which were deposited at various substrate temperatures was carried out.  2. EXPERIMENTAL DETAILS  Chalcogenide films were obtained by the CSVS tech-nique on well-cleaned glass substrates from stoichiometric powder in VUP-5M vacuum equipment using the follow-ing conditions: constant evaporator temperatures were Tevp = 1273 K (ZnS); 1073 K (ZnSe), 973 K (ZnTe); the substrate temperature was varied in the range of Tsub = (373-673) K for ZnSe and Tsub = (423-823) K for ZnS and ZnTe; and the time of evaporation t = 10 min. The detailed description of the deposition device is presented in [8]. Raman spectroscopic measurements were performed at room temperature (297 K) with a TRIAX 550 (1800 grooves/mm) spectrometer, using as excitation sources a He-Cd laser with wavelengths of 325 nm (for ZnS films) and 441.6 nm(for ZnSe films) and an Ar+ laser with a wavelength of 514.5 nm (for ZnTe films). The dispersed signal was detected with a liquid-nitrogen-cooled charge-coupled-device (CCD) detector array. Each spectrum was accumulated 20 times with an acquisition time of 5 sec. each. Long-pass Raman edge filters were used to elimi-nate Rayleigh scattered light from the laser. 3. RESULTS AND DISCUSSION  Figure 1 (a) shows the Raman spectra of ZnSe thin films grown at various substrate temperatures. All of   Fig. 1 – Raman spectra of ZnSe films (a) and a detailed view of the 1LO peak (b) for samples grown at indicated substrate tem-peratures. The dotted line indicates the 1LO frequency for sin-gle-crystal ZnSe b) a)  H. CHEONG, D. NAM, M.M. IVASHCHENKO, ET AL. PROC. NAP 1, 03TF21 (2012)   03TF21-2    Fig. 2 – Raman spectra of ZnS films (a)  and a detailed view of the 4LO peak (b) for samples grown at indicated substrate temperatures. The inset of (a) shows the 1LO peak, with the dotted line indicating the 1LO frequency for single-crystal ZnS      Fig. 3 – Raman spectra of ZnTe films (a) and the inset shows the 1LO peak (b), with the dotted line indicating the 1LO fre-quency for single-crystal ZnTe. A detailed view of the 2LO peak for samples grown at indicated substrate temperatures. The dotted line indicates the 2LO frequency for single-crystal ZnTe the samples show the LO mode of ZnSe at around 250 cm–1, which is close to the known frequency for a crys-tal [9-10] at 252 cm–1. Also, LO mode replicas are shown for at least up to the fourth order. The LO mode is redshifted relative to the single-crystal ZnSe case. As the temperature of the glass substrate changes, it shifts appreciably as shown in Fig. 1 (b).  When  the substrate  temperature was 373 K, the 1LO appears at 249 cm–1, and it shifts to 250, 247, 251, and 251 cm–1 at substrate temperatures of 473, 523, 623, and 673 K, respectively (Table 1). This shift is attributed to the change in the lattice constant caused by induced strain from the substrate. The mis-match in the thermal expansion coefficient of the sub-strate and the ZnSe thin films would create biaxial strain in the thin film. The redshift indicates a tensile strain. Up to 553 K, the shift gets larger with increased substrate temperature, which indicates that the in-duced strain also gets larger. For substrate tempera-tures higher than 653 K, the peak coincides with the 1LO of single-crystal ZnSe, which indicates that the strain is relaxed for these films.  Figure 2 (a) shows the Raman spectra of ZnS thin films deposited at various substrate temperatures. All of the samples show the 1LO mode of ZnS at 352 cm–1 and its replicas, which is close to the known frequency for single-crystal ZnS [10]. The 1LO mode is blueshifted relative to the single-crystal case [inset of Fig. 2(a)], which indicates compressive strain. Unlike ZnSe thin films, the peaks do not shift as the Tsub changes (Ta-ble 1). The higher order do not show any shift, either [Fig. 2(b)]. We can conclude that the overall compres-sive strain in ZnS is not strongly dependent on the sub-strate temperature.  Figure 3 (a) shows the Raman spectra of ZnTe thin films deposited at various substrate temperatures. All of the samples show the LO mode of ZnTe at around 207 cm–1  which  is  close to that of a ZnTe crystal at 208 cm–1 [11]. The 1LO peak for all the samples seem to coincide within experimental uncertainties. However, the higher order 2LO and 3LO modes show small but definitive shifts with the substrate temperature [Fig. 3(b)]. The trend of peak position shift is somewhat simi-lar to the ZnSe case. The peak redshifts up to Tsub = 623 K and then blueshifts toward the bulk peak posi-tion as the substrate temperature gets higher (Table 1). Since the redshift is smaller than the case of ZnSe, the strain relaxation occurs at a higher substrate tempera-ture. Furthermore, the 2LO peak frequency for the sample grown at Tsub = 823 K does not coincide with that of single crystal ZnTe unlike the case of ZnSe. This indicates that the strain is not fully relaxed. This is also consistent with the smaller redshift. Judging from the amount of the peak shift, we may conclude that the built-in strain is largest for ZnSe and smallest for ZnS.  4. CONCLUSIONS  We have investigated ZnS, ZnSe, and ZnTe thin films deposited by close-spaced vacuum sublimation technique by Raman spectroscopy. All of the samples show their LO modes and the replicas which demon-strate their high quality. Their shifts are interpreted as a) b) b) a)  RAMAN INVESTIGATION ON ZNS, ZNSE, ZNTE… PROC. NAP 1, 03TF21 (2012)   03TF21-3 being due to the built-in strain caused by thermal ex-pansion mismatch between the substrate and the film. ZnSe and ZnTe thin films grown at higher substrate temperatures exhibit strain relaxation. We can con-clude that the built-in strain is largest for ZnSe and smallest for ZnS.  Table 1 – List of Raman peak frequencies in investigated films   ZnSe Tsub 373 K 473 K 553 K 653 K 673 K  cm–1 eV cm–1 eV cm–1 eV cm–1 eV cm–1 eV 1LO 250 0.0310 249 0.0309 248 0.0308 249 0.0309 251 0.0309 2LO 494 0.0613 497 0.0616 491 0.0609 501 0.0621 500 0.0621 3LO 743 0.0921 746 0.0925 735 0.0911 749 0.0929 749 0.0929 4LO 995 0.1230 995 0.1230 984 0.1220 998 0.1240 998 0.1240  ZnS Tsub 423 K 523 K 623 K 723 K 823 K  cm–1 eV cm–1 eV cm–1 eV cm–1 eV cm–1 eV 1LO 352 0.0436 352 0.0436 352 0.0436 352 0.0436 352 0.0436 2LO 699 0.0867 699 0.0867 699 0.0867 699 0.0867 699 0.0867 3LO 1046 0.1300 1046 0.1300 1046 0.1300 1046 0.1300 1046 0.1300 4LO 1395 0.1730 1395 0.1730 1395 0.1730 1395 0.1730 1395 0.1730  ZnTe Tsub Ts = 423 K Ts = 523 K Ts = 623 K Ts = 723 K Ts = 823 K  cm–1 еV cm–1 eV cm–1 eV cm–1 eV cm–1 еV 1LO 207 0.0257 207 0.0257 203 0.0255 207 0.0257 207 0.0257 2LO 410 0.0508 410 0.0508 409 0.0507 411 0.0510 411 0.0510 3LO 615 0.0763 615 0.0763 614 0.0761 616 0.0764 616 0.0764 4LO 821 0.1020 821 0.1020 819 0.1020 - - - -   ACKNOWLEDGEMENTS This research was supported by the Ministry of Ed-ucation and Science of Ukraine (Grant no. 0110U001151: “CdTe and CdTe-based solid – solutions thin films for solar cells and radiation detectors”, the Ukraine State Agency for the Science, Innovation and Information and by the NRF grant funded by the MEST of Korea (2011-0019204).    REFERENCES  1. P. Mahawela, G. Sivaraman, S. Jeedigunta, et al., Mat. Scien. Engin. B 116, 283 (2005). 2. S. Kasap, P. Capper, The Springer Handbook of Electronic and Photonic Materials (Berlin: Springer: 2007). 3. D. Lincot, Thin Solid Films 487, 40 (2005). 4. L.X. Shao, K.H. Chang, H.L. Hwang, Appl. Suf. Sci. 212, 305 (2003). 5. A. Lopez-Otero, Thin Solid Films 49, 3 (1978). 6. V.P. Venkata Shubbaiah, P. Prathap, and K.T.R. Reddy, Appl. Surf. Sci. 253, 2409 (2006). 7. P. Prathap, N. Revathi, Y.P. Venkata Subbaiah, and K.T.R. Reddy, J. Phys.: Condens. Matter 20, 035205 (2008). 8. V.V. Kosyak, А.S. Оpanasyuk, P.M. Bukivskij, Yu.P. Gnatenko. J. Crystal Growth 312, 1726 (2010). 9. D. Schmeltzer, R. Beserman, J. Phys. C: Solid State Phys. 15, 4173 (1982). 10. O. Madelung, Semiconductors: Data Handbook, (Berlin: Springer: 2004). 11. J.C. Irwin, J. Lacombe, J. Appl. Phys. 41, 1444 (1970). 

Raman Investigation on ZnS, ZnSe, ZnTe Thin Films Obtained by CSVS Technique

SocioEconomic Challenges Journal (Sumy State University)

Raman Investigation on ZnS, ZnSe, ZnTe Thin Films Obtained by CSVS Technique

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Electronic Sumy State University Institutional Repository

SocioEconomic Challenges Journal (Sumy State University)