Abstract
This thesis concerns the conception, growth and characterization of InAs/GaSb superlattices (SL), for the realization of infrared photodetectors operating at room temperature (RT) in the 3-5 μm wavelength range. The first part of this manuscript deals with an introduction and a state of the art on infrared detection. We present the advantages of superlattice infrared photodetectors (SLIPs) and explain why the InAs/GaSb system is a promising candidate for the third generation of cameras. The second part is devoted to the fabrication of the SL by EJM on GaSb substrate. Strain compensation of the SL by the insertion of InSb at the GaSb-on-InAs interface is studied, as well as the influence of various parameters (growth temperature, element five beam equivalent pressure, ...). Rugosity measurements by AFM, HRDX and photoluminescence caracterisations shows that we achieved a high quality material, and thick SL (up to 2.5 μm) has been grown. P-i-n SLIPs with a cut-off wavelength of 5.6 μm are presented in the last part. These devices, with a mesa geometry showed RT operation with R0A~2-4.10-3 Ω.cm² , a sensibility of 80 mA/W at 0 V and a calculated specific detectivity at 4 μm of 4.107 cmHz0.5/W. A slight improvement is obtained by inserting an Al0.4GaSb layer at the buffer/SL interface: R0A~6.10-3 Ω.cm² , a sensibility of 300 mA/W at -0.4 V leading to a calculated specific detectivity at 4 μm of 7.107 cmHz0.5/W. A strong improvement is predicted by modifying the design of the device (asymmetrical SL, interfaces with contact layers....), and above all, by passivating properly the mesa device.