Skip to main content Accessibility help

Efficient Near Infrared Si/Ge Quantum Dot Photo-Detector Based on a Heterojunction Bipolar Transistor

  • Anders Elfving (a1), Mats Larsson (a1), Per-Olof Holtz (a1), Göran V. Hansson (a1) and Wei-Xin Ni (a1)...


Ge dots embedded in Si offer the possibility of Si-based light detection at 1.3-1.55 μm. In this communication, we report a very efficient photo-detector based on a Si/SiGe heterojunction bipolar transistor structure with 10 Ge dot layers (8 ML Ge each) incorporated in the basecollector junction. The device structures were grown using low-temperature molecular beam epitaxy, and fabricated for both normal and edge incidence with no electrical contact to the base. The processed Ge-dot transistor detectors revealed a rather low dark current density, 0.01 mA/cm2 at -2 V. Photoconductivity measurements were performed at room temperature. At 1.31 μm, responsivity values of 50 mA/W at normal incidence have been directly measured at Vce = -4 V, without involving any rescaling factor due to light coupling. This value is a ∼250-fold increase compared to a reference p-i-n diode with the same dot layer structure, due to the current amplification function of the transistor. For a rib waveguide device, a very high responsivity value of about 470 mA/W (Vce = -4V) has been obtained at 1.31 μm. Measurements were also performed at 1.55 μm, and the photo-response of the waveguide phototransistor was 25 mA/W, which is again a large improvement compared with the reference waveguide photodiode (∼1 mA/W). Moreover, time-resolved photoconductivity measurements have been carried out. The results have indicated that the device frequency performance is primarily limited by the emitterbase junction capacitance.



Hide All
1. Colace, L., Masini, G., Assanto, G., Luan, Hsin-Chiao, Wada, K. and Kimmerling, L.C., Appl. Phys. Lett. 1231, 1231 (2000).
2. Eaglesham, D.J. and Cerullo, M., Phys. Rev. Lett. 1943, 1943 (1990).
3. Asai, M., Ueba, H. and Tatsuyama, C., J. Appl. Phys. 2577, 2577 (1985).
4. Brunner, K., Reports on Progress in Physics 27, 27 (2002).
5. Tong, S., Liu, J.L., Wan, J. and Wang, Kang L., Appl. Phys. Lett. 1189, 1189 (2002).
6. Elkurdi, M., Boucaud, P., Sauvage, S., Kermarrec, O., Campidelli, Y., Bensahel, D., Saint-Girons, G. and Sagnes, I., Appl. Phys. Lett. 509, 509 (2002).
7. Elkurdi, M., Boucaud, P., Sauvage, S., Fishman, G., Kermarrec, O., Campidelli, Y., Bensahel, D., Saint-Girons, G., Sagnes, I. and Patriarche, G., J. Appl. Phys. 1858, 1858 (2002).
8. Elkurdi, M., Boucaud, P., Sauvage, S., Fishman, G., Kermarrec, O., Campidelli, Y., Bensahel, D., Saint-Girons, G., Patriarche, G. and Sagnes, I., Phys. E 523, 523 (2003).
9. Elfving, A., Hansson, G.V. and Ni, W.-X., Phys. E 528, 528 (2003).
10. Elfving, A., Larsson, M.. Holtz, P.-O., Hansson, G.V. and Ni, W.-X., to be published in Appl. Phys. Lett.
11. Ni, W.-X., Elfving, A.,Larsson, M., Hansson, G.V. and Holtz, P.-O., invited paper in the Proc. of the 3rd International Conference on SiGe(C) Epitaxy and Heterostructures, pp. 251254 (Santa Fe, March 9-12, 2003).
12. Humlicek, J. in Properties of silicon germanium and SiGe:carbon, edited by Kasper, E. and Lyutovich, K. (EMIS data review series no. 24, INSPEC, IEEE, London, 2000) pp. 249259.
13. Ni, W.-X., Ekberg, J.O., Joelsson, K.B.,Radamson, H.H., Henry, A., Shen, G.-D. and Hansson, G.V., J. Crystal Growth 285, 285 (1995).
14. Du, C.-X., Ni, W.-X., Joelsson, K.B., Duteil, F. and Hansson, G.V., J. Luminescence, 329, 329 (2002).
15. Schmidt, O.G., Lange, C. and Eberl, K., Appl. Phys. Lett. 1905, 1905 (1999).
16. Kienzle, O., Ernst, F., Rühle, M., Schmidt, O.G. and Eberl, K., Appl. Phys. Lett. 269, 269 (1999).


Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed