Naslov
Broadband PureGaB Ge-on-Si photodiodes responsive in the ultraviolet to near-infrared range

Autori
Knežević, Tihomir ; Krakers, Max ; Nanver, Lis K.

Vrsta, podvrsta i kategorija rada
Radovi u zbornicima skupova, cjeloviti rad (in extenso), znanstveni

Izvornik
Proceedings SPIE 11276, Optical Components and Materials XVII, 112760I / - : SPIE, 2020

Skup
SPIE OPTO: Optical Components and Materials XVII

Mjesto i datum
San Francisco (CA), Sjedinjene Američke Države, 01.02.2020. - 06.02.2020

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
broadband photodiode, ultraviolet photodiode, near-infrared photodiode, Ge-on-Si, Ge diodes, pure gallium and pure boron (PureGaB), responsivity, light emission measurements, simulations

Sažetak
Optical characterization of PureGaB germanium- on-silicon (Ge-on-Si) photodiodes was performed for wavelengths between 255 nm and 1550 nm. In PureGaB technology, chemical vapor deposition is used to grow germanium islands in oxide windows to the silicon substrate and then cap them in-situ with nm-thin layers of first gallium and then boron, thus forming nm-shallow p+n diodes. These PureGaB Ge-on-Si photodiodes are CMOS compatible and characterized by low leakage currents. Here they are shown to have high responsivity in the whole ultraviolet (UV) to near infrared (NIR) wavelength range. Particularly, two sets of diodes were studied with respect to possible detrimental effects of the Al metallization/alloying process steps on the responsivity. Al-mediated transport of the Ge and underlying Si was observed if the PureGaB layer, which forms a barrier to metal layers, did not cover all surfaces of the Ge islands. A simulation study was performed confirming that the presence of acceptor traps at the Ge/Si interface could decrease the otherwise high theoretically attainable responsivity of PureGaB Ge-on-Si photodiodes in the whole UV to NIR range. A modification of the device structure is proposed where the PureGaB layer covers not only the top surface of the Ge-islands, but also the sidewalls. It was found that to mitigate premature breakdown, it would be necessary to add p-doped guard rings in Si around the perimeter of Ge islands, but this PureGaB-all-around structure would not compromise the optical performance.

Izvorni jezik
Engleski

Znanstvena područja
Elektrotehnika

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