Effects of surface oxide formation on germanium nanowire band-edge photoluminescence

Hashemi, Fatemeh; Thombare, Shruti V.; Morral, Anna Fontcuberta i; Brongersma, Mark L.; McIntyre, Paul C.

doi:10.1063/1.4812334

Cited by 20 publications

(12 citation statements)

References 41 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We find that annealing in forming gas (hydrogen and nitrogen) at 350 °C increases the forward current by more than 50×. We attribute this to improved electrical contact between the metal on the tops of the nanowires and the graphene, as well as further passivation of surface states on the sidewall of the nanowires. , …”

Section: Passivation By Silicon Dioxidementioning

confidence: 76%

Vertical Ge–Si Nanowires with Suspended Graphene Top Contacts as Dynamically Tunable Multispectral Photodetectors

Solanki

Frigerio

et al. 2019

ACS Photonics

View full text Add to dashboard Cite

Numerous applications would be enabled by pixels for multispectral imaging whose spectral responses can be dynamically tuned and that can be potentially manufactured at low cost. Here, we show such a capability, by experimentally demonstrating arrays of vertically-oriented germanium-silicon heterojunction nanowires with graphene top contacts. Our devices present opportunities for multispectral imaging because their responsivity spectra can be tailored by choice of nanowire radius for enhanced absorption at certain wavelengths across the visible to shortwave infrared. Importantly, these responsivity spectra can also be dynamically tuned by bias voltage. We demonstrate this experimentally by tuning the responsivity peak of a single pixel across the visible region by varying the bias voltage and by showing that this would allow red/green/blue channels to be reconstructed. This opens the exciting prospect of a single pixel that can resolve color (i.e. replacing the three red/green/blue pixels of traditional approaches) or even resolve several bands for multispectral imaging.

show abstract

Section: Passivation By Silicon Dioxidementioning

confidence: 76%

Vertical Ge–Si Nanowires with Suspended Graphene Top Contacts as Dynamically Tunable Multispectral Photodetectors

Solanki

Frigerio

et al. 2019

ACS Photonics

View full text Add to dashboard Cite

show abstract

“…The presence of germanium oxide is important because it strongly influences the performance of Ge QD-based devices. , The oxidation of Ge was investigated with XANES. The results are shown in Figure .…”

Section: Resultsmentioning

confidence: 99%

Ge Quantum Dots Coated with Metal Shells (Al, Ta, and Ti) Embedded in Alumina Thin Films for Solar Energy Conversion

Basioli

Sancho‐Parramon

Despoja

et al. 2020

ACS Appl. Nano Mater.

View full text Add to dashboard Cite

A method to enhance the optoelectronic properties of thin films containing three-dimensional ordered germanium quantum dots (QDs) coated with metal shell (Al, Ta, and Ti) in alumina matrix is presented. The conditions for the achievement of self-assembled growth of the metal-coated Ge QDs by magnetron sputtering deposition are explored. The influence of the metal shell on the structural, optical, and optoelectronic properties is found to be radical and desirable. First, it reduces Ge oxidation. Second, it enhances overall absorption by an order of magnitude. Third, it enables manipulation of the absorption curve shape in two ways. The Ge absorption peak, useful for photoelectric conversion, can be tuned significantly via control of the Ge energy gap because of the quantum confinement effect. On the other hand, infrared absorption can be controlled by the amount of metal because the geometry of the system can enhance absorption in the core by excitation of plasmon resonances in the shell. The mentioned effects result in a high increase of the photocurrent and quantum efficiency of core−shell nanoparticles compared to simple Ge particles. The experiments are supported by theoretical predictions, showing that the intensity of the incident radiation is strongly amplified in the region around the metal−semiconductor interface upon the excitation of plasmon resonances, hence increasing the probability of photon absorption and, thus, of charge carrier generation in the photo-active material. Therefore, the presented materials are very promising for photoelectric devices.

show abstract

“…18,20) A suitable surface/interface passivation for Ge should be required, as in the case for Ge-channel metal-oxidesemiconductor field effect transistors. [21][22][23] So far, an enhanced photoluminescence (PL) intensity has been reported for surface-oxidized Ge 24) and Ge nanowires, 25) although no quantitative analysis on the recombination velocity at the Ge/GeO 2 interface has been reported yet. We have also reported a PL enhancement for Ge mesa structures selectively grown on Si after a wet chemical treatment in a CH 3 COOH/HNO 3 /HF/I 2 solution to induce a preferential etching of Ge near the defectrich Ge/Si interfaces.…”

Section: Introductionmentioning

confidence: 99%

Impact of interface recombination on direct-gap photoluminescence from Ge epitaxial layers on Si

Yako

Higashitarumizu

Ishikawa

2019

Jpn. J. Appl. Phys.

View full text Add to dashboard Cite

Direct-gap photoluminescence (PL) at the wavelength around 1.55 μm from Ge epitaxial layers on Si is studied toward Ge lasers in Si photonics. Comparing the PL intensities under two different wavelengths of excitation lasers, non-radiative interface recombination velocities are estimated to be as large as 105 cm s−1 at Ge/Si and Ge/air interfaces, whereas that at the Ge/GeO2 interface is estimated to be as small as 103–104 cm s−1, which is required for the threshold current density in Ge lasers as low as 10 kA cm−2. In order to remove the effect of defect-rich Ge/Si hetero-interfaces with a high recombination velocity, a wet chemical treatment in a CH3COOH/HNO3/HF/I2 solution is examined. A preferential etching of Ge at Ge/Si interfaces leads to an enhancement of the PL peak intensity by 83 times. A suppression of non-radiative recombination at the Ge/Si interface should contribute to this enhancement, and such a suppression plays a critical role for Ge lasers.

show abstract

Effects of surface oxide formation on germanium nanowire band-edge photoluminescence

Abstract: Alternative surface passivation on germanium for metal-oxide-semiconductor applications with high-k gate dielectric Appl.

Cited by 20 publications

References 41 publications

Vertical Ge–Si Nanowires with Suspended Graphene Top Contacts as Dynamically Tunable Multispectral Photodetectors

Vertical Ge–Si Nanowires with Suspended Graphene Top Contacts as Dynamically Tunable Multispectral Photodetectors

Ge Quantum Dots Coated with Metal Shells (Al, Ta, and Ti) Embedded in Alumina Thin Films for Solar Energy Conversion

Impact of interface recombination on direct-gap photoluminescence from Ge epitaxial layers on Si

Contact Info

Product

Resources

About