Molecular beam epitaxial growth and characterization of extended short wavelength infrared mercury cadmium telluride detectors

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Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, Elektrik ve Elektronik Mühendisliği Bölümü, Türkiye

Tezin Onay Tarihi: 2017

Öğrenci: EMRAH ŞAŞMAZ

Danışman: CENGİZ BEŞİKCİ

Özet:

This thesis reports the growth, fabrication and characterization of extended short wavelength infrared (SWIR) mercury cadmium telluride (Hg1-xCdxTe) photodiodes with a cut off wavelength of 2.17 µm at room temperature. HgCdTe layers were grown on home-polished cadmium zinc telluride, CdZnTe, substrates by molecular beam epitaxy (MBE). Test arrays were fabricated in order to evaluate the electrical and optical characteristics of the photodiodes. Test array consists of mesa type pixels with 30 µm pitch. The test array was hybridized with silicon fan-out with flip-chip bonder. Electrical and optical characterization performed on 28x28 µm2 detectors yielded a room temperature dark current density of 100 µA/cm2 which is diffusion limited. The peak responsivity of the test diodes without anti-reflection coating is 1.0 A/W corresponding to a quantum efficiency of 62%. Dark current limited peak detectivity of the detectors is 1.17x10^11 Jones at room temperature. Deep level transient spectroscopy (DLTS) measurements were performed on the detectors in order to identify the performance limiting material characteristics. DLTS measurements yielded a hole trap with activation energy of 267 meV, capture cross section of 2.0x10^-17 cm2 and trap density of 3x10^13 cm-3. The trap does not display extended defect characteristics suggesting that it originates from isolated defects in the material