Sensori ed emettitori di luce nell'infrarosso basati su tecnologia al germanio per l'integrazione col silicio

Responsabili di progetto

Claudio Ferrari, Sevda Abdullayeva

Accordo

AZERBAIJAN - ANAS-not in force - Azerbaijan National Academy of Sciences

Bando

CNR/ANAS 2014-2015

Dipartimento

Ingegneria, ICT e tecnologie per l'energia e i trasporti

Area tematica

Ingegneria, ICT e tecnologie per l'energia e i trasporti

Stato del progetto

Nuovo

Proposta di ricerca

The goal of this project is to develop a semiconductor voltage-tunable sensor for visible and near-infrared bands integrated on the same chip, fabricated using Germanium on Silicon technology with a novel design of light detecting. The realization of this simple device will allow in the future the preparation of an image sensor based on silicon with tunable sensitivity between visible and near infrared range for surveillance and security applications.
Multi-band imaging is a relatively new approach which combines spectroscopic and spatial information. It extracts more information with respect to the so-called panchromatic imaging, where pixels record only the total intensity of radiation.

This technique has several applications in chemistry, astronomy, biology, medicine and remote sensing (including military and security) [1]. It can be performed by using several cameras that operate in different spectral bands or by using wide band cameras provided with tunable pass-band filters or dispersive optical systems (spectrometers) to select the range of interest [2]. Multi-band imagers are typically complex, expensive, bulky; they often require multiple exposures and extensive post-processing. It is only recently that research efforts have been devoted towards more compact and integrated solutions. Dual band for medium wavelength infrared (MWIR) and long wavelength infrared (LWIR) were previously proposed and demonstrated, with both independent and simultaneous detection and voltage tunability, using arrays of quantum well infrared detectors in III-V compound semiconductors [3]. Much less work has been done in the VIS-NIR bands. In these spectral ranges only NIR-enhanced silicon CCD or CMOS arrays [4] or VIS-enhanced InGaAs [5] have been fabricated with multi-band operation eventually obtained by filtering. As of today, VIS-NIR voltage tunable image sensors are not available.

Another important field of research concerning germanium and its integration with silicon is the preparation of germanium based light emitting diodes (LED) working in the infrared region, suitable for fiber communications. Even if there is a 4% lattice mismatch with respect to silicon the integration of germanium devices in the silicon platform is by far much easier that the integration of other direct band gap III-V compounds due to its non polar structure. Unfortunately the (nearly) indirect band gap of germanium makes the radiant recombination process, on which LEDs are based, highly unfavoured. The radiant recombination efficiency can be stimulated by preparing highly doped p+-n Ge junctions [6], by inducing a strain in the Ge layers, or at high current values by electroluminescence due to the saturation of the lowest conduction band levels at high current values [7].


[1] P. Colarusso, L.H. Kidder, I.W. Levin, J.C Fraser, J.F. Arens, E.N. Lewis, "Infrared Spectroscopic Imaging: From Planetary to Cellular Systems ", Appl. Spectr., 52, 106, 1998.
[2] C.D. Tran, "Principles, Instrumentation, and Applications of Infrared Multispectral Imaging, An Overview", Analytical Lett., 38, 735, 2005.
[3] M.H Hostut, K. Kilic, S. Sakiroglu, Y. Ergun, I. Sokmen, "Voltage tunable Dual-band quantum well infrared photodetector for third generation thermal inaging", IEEE Phot. Technol. Lett. 23, 1370, 2011.
[4] B. Tsaur, C.K. Chen, J. Mattia "PtSi schottky-barrier focal plane arrays for multispectral imaging in ultraviolet, visible and infrared spectral bands", IEEE Electron Dev. Lett. 11, 162, 1990.
[5] M.H. Ettenberg, M.J. Lange, T. O'Grady, J.S. Vermaak, M.J. Cohen, G.H. Olsen, A room temperature 640x480 pixel near-infrared InGaAs focal plane array", Proc. SPIE, 4028, 201, 2000.
[6] Szu-Lin Cheng, Jesse Lu, Gary Shambat, Hyun-Yong Yu, Krishna Saraswat, Jelena Vuckovic and Yoshio Nishi, "Room temperature 1.6 ¼m electroluminescence from Ge light emitting diode on Si substrate", 8 June 2009 / Vol. 17, No. 12 / Optic Express 10019
[7] M. de Kersauson, R. Jakomin, M. El Kurdi,,a G. Beaudoin,N. Zerounian, F. Aniel, S. Sauvage,. Sagnes, and P. Boucaud, "Direct and indirect band gap room temperature electroluminescence of Ge diodes ", J. of Appl. Phys. 108, 023105 2010

Obiettivi della ricerca

The project is aimed at realizing:
Silicon/Germanium (Si/Ge) sensor for operation in both the visible and the near-infrared. Voltage tunable photodetectors will be designed in order to be able to weigh VIS and NIR contributions. This is done by preparing Ge and Si dioded with back to back connection. The polarization of the devices permits to activate one of the two junctions alternatively. The Ge/Si technology has been selected to combine the short wavelength sensitivity (300-900nm) and the superior capability of silicon technology with the NIR sensitivity (800-1800nm) of germanium.

- Structures of highly doped Ge-based light emitting diodes on germanium and, if possibe virtuals substrates based on Germanium on silicon. The success of this last task would have important applications in fully integrated optoelectronic devices based on the silicon platform.

We propose a novel epitaxial growth procedure of germanium based devices based on the use of isobutyl germane (iBuGe) which is a novel metal organic precursor having high vapour pressure at room temperature, low backgound impurity level. Moreover, it is considerably less toxic than germane and is therefore a suitable candidate for the realization of epitaxial junction in a MOVPE apparatus using the conventional temperature

Ultimo aggiornamento: 19/04/2024