Yüksek hızlı ve yüksek verimli kızılötesi fotodedektörler

AbstractHIGH SPEED AND HIGH EFFICIENCY INFRAREDPHOTODETECTORSİbrahim KimukinPh. D. in PhysicsSupervisor: Prof. Ekmel ÖzbayDecember 2004The increasing demand for telecommunication systems resulted in productionof high performance components. Photodetectors are essential components ofoptoelectronic integrated circuits and fiber optic communication systems. Wesuccessfully used resonant cavity enhancement technique to improve InGaAsbased p-i-n photodetectors. The detectors had 66% peak quantum efficiency at1572 nm which showed 3 fold increases with respect to similar photodetectorwithout resonant cavity. The detectors had 28 GHz 3-dB bandwidth at the sametime. The bandwidth efficiency product for these detectors was 18.5 GHz, which isone of the best results for InGaAs based vertical photodetector.The interest in high speed photodetectors is not limited to fiber optic networks.In the recent years, data communication through the air has become popular due toiease of installation and flexibility of these systems. Although the current systemsstill operate at 840 nm or 1550 nm wavelengths, the advantage of mid-infraredwavelengths will result in the production of high speed lasers and photodetectors.InSb based p-i-n type photodetectors were fabricated and tested for the operationin the mid-infrared (3 to 5 µm) wavelength range. The epitaxial layers were grownon semi-insulating GaAs substrate by molecular beam epitaxy method. Thedetectors had low dark noise and high differential resistance around zero bias.Also the responsivity measurements showed 49% quantum efficiency. Thedetectivity was measured as 7.98×109 cm Hz1/2/W for 60 µm diameter detectors.Finally the high speed measurements showed 8.5 and 6.0 GHz bandwidth for 30µm and 60 µm diameter detectors, respectively.Keywords: Photodetector, high speed, high efficiency, resonant cavityenhancement, infrared wavelengths.ii