Search for content and authors
 

Silicon planar source of modulated infrared radiation

Tadeusz Piotrowski 1Maciej Węgrzecki 1Henryk Polakowski 2Vladimir K. Malyutenko 3Andrzej Czerwinski 1

1. Institute of Electron Technology (ITE), al. Lotników 32/46, Warszawa 02-668, Poland
2. Military University of Technology (WAT), Kaliskiego 2, Warszawa 00-908, Poland
3. Lashkarev Institute of Semiconductor Physics, NASU, Pr. Nauki 45, Kyiv 03028, Ukraine

Abstract

This paper presents results of the theoretical analysis and the experimental verification of influence of geometrical parameters of a planar silicon structure emitting the modulated infrared radiation in a wide and continuous spectral range 3-12 μm.The approach is based on the modulation of the thermal emission power of semiconductors in the spectral range of intraband electron transitions. The free-carrier absorption-emission processes are utilized in techniques of dynamic emissivity enhancement. The emitting area was constituted by the base of a p-i-n structure operating well above room temperatures. The signal modulation was realized by the contact injection of free carriers. The changes of current-carrier concentration in the base of p-n diode influence the absorption coefficient (α), therefore also the emissivity (ε), thus allowing for modulation of infrared radiation emitted from the heated structure. Optimization of the structure parameters was aimed at maximal difference between emissivity of this structure heated to about 450K, for cases with and without forward bias applied to the p-n junction. Nearly 1.0 mW output power was achieved at T ~ 450 K with ~0.8 % external power conversion efficiency. The difference of emissivity can be described by: ΔεR = (1-R1)(R2η2+1)(1-η2)/(1-R1R2η22)-(1-R1)(R2η1+1)(1-η1)/(1-R1R2η12), where η = exp(-αλd), R - reflection coefficient, αλ - absorption coefficient at wavelength λ. This equation was applied for calculation of thickness d that enables maximal ΔεR at specific values of R and α. It was shown that high ΔεR for wafers with typical thickness (0.05 cm) requires an application of mirrors with R>0.8. This planar device based on the transparency modulation technique enhanced by the reflecting mirror on the back facet is easy to produce using standard silicon technology. It can be applied for diode matrix used for testing of dynamic characteristics of thermal cameras and generation of infrared imagery.

 

Legal notice
  • Legal notice:
 

Related papers

Presentation: Poster at E-MRS Fall Meeting 2009, Symposium D, by Andrzej Czerwinski
See On-line Journal of E-MRS Fall Meeting 2009

Submitted: 2009-05-06 17:12
Revised:   2009-08-13 17:30