Responsabilidad del Estado Peruano

2.6.0 Comments

This review represented a range of silicon based optical materials and considered a number of mechanisms by which visible light emission may occur in these materials. There are a many studies concerning this general topic and particularly in the area o f porous silicon particularly in the period of 1991-1995 and this review has attempted to cover all the main proposed mechanisms. However, it would be reasonable to state that the consensus is that quantum confinement of the nanoclustered silicon is at least in part responsible for the visible light emission. Moreover, possible entirely so in the case of porous silicon.

2.6.1 Postulated visible photoluminescence mechanisms

The postulated mechanisms that can produce visible photoluminescence in SiOx and related materials are the following:

1) Quantum confinement of excitons in the silicon cluster with recombination in the cluster.

It is also established that quantum-confinement will; enhance oscillator strength as cluster size decreases, red-shift the luminescence with an increase in cluster

C h apter Two: Literature review o f ligh t em ission fro m silicon b a sed m aterials

size and evoke relaxation in the crystal momentum making radiative transitions more likely.

2) Quantum confinement of excitons in the silicon cluster with recombination at the cluster-matrix interface.

This is similar to the above but may alter the photoluminescence depending on the surface states at the cluster-matrix interface.

3) Luminescent defects in SiOx and Si0 2.

It is widely observed that these defects are annealed out of the films at 500- 600°C and generally luminescent at 2.0-2.2eV. This annealing behaviour is linked to removal of hydrogen initially creating more luminescent defect centres (increasing the photoluminescence intensity of this band) and at higher temperatures diffusing oxygen bonding to hole sites leading to a decrease (or extinction) in photoluminescence intensity. This topic is covered in detail in chapter seven. Chou et. a l [37] studying implanted Si into Si0 2 have also noted

a band at 1.9eV (ascribed to non-bridging oxygen hole centres) that is closely related by Chou to the Si-O-H structure. This band appears in these films at anneals up to 800°C.

4) Alloys of Si-H and SiN at the interface of the cluster and/or in the film matrix. Photoluminescence (and electroluminescence) demonstrated in material produced solely of these alloys and it a variety of partially oxidised derivatives. Evidence of photoluminescence from alloys is dismissed in studies of porous silicon.

5) Siloxene and derivatives

W hile siloxenes are often regarded as a possible source of photoluminescence in these types of materials (especially porous silicon) the scope for such molecules

C h apter Two: Literature review o f light em ission from silicon b a sed m aterials

to exhibit Photoluminescence in the SiOx system is unlikely and no research could be found that supported this view. This is possibly due to the rigid structure that exists in PECVD grown SiOx that suppresses the growth of large molecules) and also that Photoluminescence is still evident after high temperature anneals that would have dissociated such molecules [31]. In light of this and the lack of information on siloxene and its derivatives in SiOx, this mechanism will not be discussed further.

References

1) D.J. DiMaria, J.R. Kirtley, E.J. Pakulis, D.W. Dong, T.S. Kuan, F.L. Pesavento, T.N. Theis, J.A. Cutro, S.D. Brorson, J. Appl. Phys. 56, 401 (1984)

2) T. Shimizu-Iwayama, S. Nakao, K. Saitoh, N. Itoh,. J. Phys. Condens. Matter,

6, L601-L606 (1994)

3) T. Komoda, J.P. Kelly, A. Nejim, K.P. Homewood, P.L.F. Hemment and B.J. Sealy, Mat. Res. Symp. Proc. 358, 163 (1995)

4) T. Shimizu-Iwayama, K. Fujita, S. Nakao, K. Saitoh, T. Fujita and N. Itoh, J. Appl. Phys. 75, 7779 (1994

5) Y. Ono, M. Nagase, M. Tabe and Y. Takahashi, Jpn. J. Appl. Phys. 34, 1728 (1995)

6) T. Fischer, T. Muschik, R. Schwarz, D. Kovalev and F. Koch, Mat. Res.

Symp. Proc. 358, 851 (1995)

7) G.S. Tompa, D C. Morton, B.S. Sywe, Y. Lu, E.W. Forsythe, J. A. Ott, D. Smith, J. Khurgin and B. A. Khan, Mat. Res. Symp. Proc. 358, 701 (1995)

8) J.B. Khurgin, E.W. Forsythe, S.I. Kim, B.S. Sywe, B.A. Khan and G.S.

Tompa, Mat. Res. Symp. Proc. 358, 193 (1995)

9) E.W. Forsythe, E.A. Whittaker, F.H. Poliak, B.S. Sywe, G.S. Tompa, B.A. Khan, J. Khurgin, H.W.H. Lee, F. Adar and H. Schaffer, Mat. Res. Symp. Proc. 358, 187 (1995)

C h apter Two: L iterature review o f light em ission fro m silicon based m aterials

10) S. Hayashi, T. Nagareda, Y. Kanzawa and K. Yamamoto, Jpn. J. Appl. Phys.

32, 3840(1993)

11) S. Nozaki, H. Nakamura, H. Ono, H. Morisaki and N. Ito, Jpn. J. Appl. Phys.

34, 122(1994)

12) Y. Osaka, K. Tsunetomom, F. Toyomura, H. Myoren, K. Kohno, Jpn. J. Appl. Phys. 31, L365 (1992)

13) S. Y. Ren, J. D. Dow, Phys Rev. B 45, 6492 (1992)

14) N. A. Hill, K. B. Whaley, Mat. Res. Symp. Proc. 358, 25 (1995) 15) S. Furukawa, T. Miyasato, Phys Rev. B 38, 5726 (1988)

16) M. Riickschloss, O. Ambacher, S. Veprek, J. of Luminescence, 57, 1-4, (1993)

17) (Q) S. Veprek, V. Marecek, Solid Stae Electron. 11, 683, (1968) 18) S. Veprek, Z. Iqbal, F. A. Sarott, Phil. Mag. B, 55, 137 (1982)

19) H. Takagi, H. Ogawa, Y. Yamazaki, A.Ishizaki, T. Nakagiri, Appl. Phys. Lett. 56, 2379 (1990)

20) B. Delley, E. F. Steigmeier, Phys. Rev. 47, 1397 (1990) 21) Y. Kanemitsu, Phys Rev. B 49, 16845 (1994)

22) K. Takeda, K. Shiraishi, Solid State Commun. 85, 301 (1993)

23) W. L. Wilson, P.F. Szajowski, L. E. Brus, Science, 262, 1242 (1993) 24) M. S. Hybersten, Am. Phys. Soc. 72, 10, 1514 (1994)

25) L. E. Brus, AM. Chem. Soc. 98, 3575 (1994)

26) X. Liu, X. Wu, X. Bao, Y. He, Appl. Phys. Lett. 64, 2, 220 (1994) 27) J.F. Du, T. Wan, b.Zhou, J. Non Cryst. Solids 164-166, 945 (1993)

28) W. Boonkosum, D. Krusngsm, S. Panyakeow, J. Appl. Phys. 32, 1534 (1993) 29) B.H. Augustine, Y. Z. Hu, E. A. Irene, L. E. McNeil, (submitted to Applied physics Letters)

30) C. Lin, S. Lee, Y. Chen, Appl. Phys. Lett. 63, 7, 902 (1993)

31) P. D. J. Calcott, K. J. Nash, L. T. Canham, M. J. Kane, D. Brumhead, J. Luminescence, 57, 257 (1993)

C h apter Two: Literature review o f light em ission fro m silicon based m aterials

32) A. Ulhir, Bell System Tech. J. 35, 333 (1956) 33) L. T. Canham, Appl. Phys. Lett. 57, 1046 (1990)

34) S. Gardelis, J. S. Rimmer, P. Dawson, B. Hamilton, R A. Kubiak, T. E. Whall, E. H. C. Parker, Appl. Phys. Lett. 59, 17, 2118 (1991)

35) P. Dumas, M. Gu, C. Syrykh, J. K. Gimewski, I. Makarenko, A. Halimaoui, F. Sal van

36) K. J. Nash, P. D. J. Calcott, L. T. Canham, M. J. Kane, D. Brumhead, J. Luminescence, 60&61, 297 (1994)

37) Shu-Tsun Chou, Jen-Hwan Tsai, Bor-Ciou Sheu, J. App. Phys. 83, 10, 5394, (1998)

C h apter Three: The PEC VD deposition system f o r fabrication o f silicon-rich silica an d E r d o p ed silicon-rich silica