1 / 20

p- type Si Homojunction Interfacial Workfunction Internal Photoemission Dual-Band Detector Responding in Near- and Far-

p- type Si Homojunction Interfacial Workfunction Internal Photoemission Dual-Band Detector Responding in Near- and Far-Infrared Regions. G. Ariyawansa Department of Physics and Astronomy Georgia State University. Outline. Introduction Types of Junction Detectors Homojunction Detectors

kita
Download Presentation

p- type Si Homojunction Interfacial Workfunction Internal Photoemission Dual-Band Detector Responding in Near- and Far-

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. p- type Si Homojunction Interfacial Workfunction Internal Photoemission Dual-Band DetectorResponding in Near- and Far-Infrared Regions G. AriyawansaDepartment of Physics and AstronomyGeorgia State University

  2. Outline • Introduction • Types of Junction Detectors • Homojunction Detectors • Heterojunction Detectors Schottky Detectors Blocked Impurity Barrier (BIB) Detectors • Si HIWIP Detector Structure • Dual-Band Detection • Impurity Transitions and Hydrogenic Model • IVT Measurements and Arrhenious Calculations • Summary and Future Studies

  3. Introduction • Multi-band IR detection is useful in numerous applications such as, • Mine Detection: The use of images in two different spectral bands can aid in the detection and reduce the number of false positives. • Military Applications: The NIR portion could be used to detect the muzzle flash while the FIR portion can be useful for determining troops and operating vehicles. • Remote Sensing: Taking the difference in the spectral information of the signal for the two bands. • Other applications: Environmental Monitoring, Medical Diagnosis, Space Astronomy Applications, Spectroscopy … • Interfacial workfunction detectors: • FIR detector designs • Broad response • Tailarable wavelength threshold • Dual-band detection

  4. Types of Junction Detectors • Homojunction Detectors • Heterojunction Detectors • Schottky Detectors • Blocked Impurity Barrier (BIB ) Detectors

  5. Schottky Detectors

  6. Blocked Impurity Barrier (BIB ) Detectors

  7. Three Types of Homojunction Detector Structures + Thermal n (Emitter) Diffusion i (Barrier) i D E E + C C n E Tunneling C D n h Field E F e Impurity Band Type I - Nd < Nc ( ECn+ >EF) Nd : Doping of Emitter Nc : Mott’s critical concentration D = (ECn+-EF) + DEC JAP 77, 915, (1995)

  8. Three Types of Homojunction Detector Structures n h i E C D D E Field C F e Impurity Band + n C + i (Barrier) n (Emitter) Type II - Nc < Nd < N0 ( ECn+ < EF < ECi ) Nd : Doping concentration of the Emitter/ Absorber Nc : Mott’s critical concentration N0 : Critical concentration E D = Eci- EF E • Fermi level is above the conduction band edge of the emitter • Emitter becomes metallic • Infrared absorption is due to free carriers JAP 77, 915, (1995)

  9. Three Types of Homojunction Detector Structures n e h E F Bias ++ n - - n i (n ) Type III - Nd > N0 ( EF > ECi ) Nd : Doping concentration of the Emitter/ Absorber N0 : Critical concentration • Fermi level is above the conduction band edge of the barrier • Conduction band edge of the Emitter and the barrier become degenerate • Space charge region at the n++ - i interface forms the barrier • Barrier height depends on the concentration and the applied field JAP 77, 915, (1995)

  10. Si HIWIP- Detector Structure • Doping • Ntc = 1.5 X 1019 cm-3 • Ne = 3 X 1018 cm-3 • Nb = 1 X 1010 cm-3 • Nbc = 1.5 X 1019 cm-3

  11. Dual-Band Detection • NIR response : Interband transitions in the Si barrier • FIR response : Intraband transitions in the structure

  12. Near-IR Response • E2TO, E1TO : Phonon assisted exciton transitions at the bang edge.

  13. Band Diagram of Si

  14. Near-/Far- IR Dual Band Response @ 5.3 K • The NIR photons are absorbed in the barrier giving rise to a transition of carriers (electron-hole pair) between conduction and valence band of the GaAs barrier. • Incident MIR/FIR photons undergo free carrier absorption in the emitter. • Threshold wavelength varies with the applied bias

  15. Hydrogenic Model

  16. Near-/Far- IR Dual Band Response @ 30 K • Labeled peaks are related to impurity transitions of Boron in Si. • Numbers assigned are in meV and numbers in parenthesis are reported values. • The strength of the peak increases with the bias and the temperature.

  17. IVT Measurements • BLIP temperature is 25 K at ± 0.9 V

  18. Arrhenious Calculations • Arrhenious calculations are not valid out of the bias range from ~ -0.5V to 0.5V • This results consistent with spectral results.

  19. Conclusion and Future Studies • A single emitter Si HIWIP dual-band detector can detect NIR and MIR/FIR radiation. • Interband transitions in Si lead to NIR response while FIR response is due to intraband transitions in the structure. • High performance of the detector demonstrate the potential applications where the detection in both NIR and FIR are important. • Future Studies >>>> • Developing a dual band detector covering UV and FIR regions. • Band tuning based on operational conditions.

  20. Thanks…

More Related