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Development of thermal detector elements based on two-dimensional photonic sislicon structures

№20 Department of photonic semiconductor structures
   L.A. Karachevtseva

1a	1b
	Рис.1а. Near infrared absorption spectra of two macroporous silicon structures and a monocrystal silicon. Рис. 1b. 500 micron thermal detector test structure with macroporous silicon layer and Al contacts:. - resistance temperature  coefficient of 3%/K; - noise level (2-5)×10-9 V×Hz-1/2.

Thermodetecting structure operates in next way:

Incident electromagnetic wave is absorbed by silicon structure 1 due to the decay electromagnetic wave formation and transition into Joule heat. The thermal element heat is saved due to low thermoconductivity of the cavity 3 between thermal element 1 and dielectric substrate 2. The change of the thermal element conductivity after heating is registrated by change of potential between metal contacts 4.

Devices on the base of two-dimentional photonic silicon structures can be used for needs of ecological monitoring of an environment, the control over medicine, productions in the industry.
Optical absorption in the range of 3-14 micron is 85-98% for thermal receiver structures of 20 micron thickness. The noise level for macroporous silicon structures 2.5·10^-9 VHz^-1/2 is determined by Johnson noise. Sensitivity of the thermodetecting element based on photonic silicon structures makes (0.8-1.2)·10³ W/K, detectivity is to D*≈2·10⁹ сmHz^1/2W^-1.

Detectivity of bolometric elements based on two-dimensional photonic silicon structures is higher in comparison with analogues due to the greater optical absorption and lower noise level. Optical absorption is much higher apparently thermal detecting structures based on amorphous and polycrystalline silicon. The noise level for macroporous silicon structures is the order value lower of noise in amorphous and polycrystalline silicon. Sensitivity of the thermodetecting element based on photonic silicon structures is much higher than in analogues.

Karachevtseva L.A., Sizov F.F., Goltvyansky Yu.V., Konin K.P., Stronska O.J., Parshin K.A., Lytvynenko O.A., UA Patent “Uncooled Thermosensitive Element for Bolometers”, № 80345 (10.09.2007).