Controlling barrier height and spectral responsivity of p-i-n based GeSn photodetectors via arsenic incorporation.

GeSn compounds have made many interesting contributions in photodetectors (PDs) over the last ten years, as they have a detection limit in the NIR and mid-IR region. Sn incorporation in Ge alters the cut off wavelength. In the present article, p-i-n structures based on GeSn junctions were fabricated to serve as PDs. Arsine (As) is incorporated to develop n-GeSn compounds via a metal induced crystallization (MIC) process followed by i-GeSn on p-Si wafers. The impact of As and Sn doping on the strain characteristics of GeSn has been studied with high resolution transmission electron microscopy (HRTEM), X-ray diffraction and Raman spectroscopy analyses. The direct transitions and tuning of their band energies have been investigated using diffuse reflectance UV-vis spectroscopy and photoluminescence (PL). The barrier height and spectral responsivity have been controlled with incorporation of As. Variation of As incorporation into GeSn Compounds shifted the Raman peak and hence affected the strain in the Ge network. UV-vis spectroscopy showed that the direct transition energies are lowered as the Ge-As bonding increases as illustrated in Raman spectroscopy investigations. PL and UV-vis spectroscopy of annealed heterostructures at 500 °C showed that there are many transition peaks from the UV to the NIR region as result of oxygen vacancies in the Ge network. The calculated diode parameters showed that As incorporation leads to an increase of the height barrier and thus dark current. Spectral response measurements show that the prepared heterojunctions have spectral responses in near UV and NIR regions that gives them opportunities in UV and NIR photodetection-applications.

Correction: Controlling barrier height and spectral responsivity of p-i-n based GeSn photodetectors via arsenic incorporation.

[This corrects the article DOI: 10.1039/D3RA00805C.].

Impact of strain engineering and Sn content on GeSn heterostructured nanomaterials for nanoelectronics and photonic devices.

Heterostructures based on the GeSn nanocompound have high impact on integrated photonics devices. The promising feature of GeSn nanostructures is its direct bandgap transition that is a result of Sn incorporation in the Ge networks, forming a strained structure. Herein, we demonstrate a deep survey of the strain-controlling mechanisms in GeSn nanomaterials with different methodologies. Using either layer configurations, Sn incorporation, or by external stressors, the emission of different photonic and nanoelectronic applications is controlled. We find that strain engineering modulates the bandgap of GeSn active media to control the region of emission for light emitting diodes, lasing applications, and spectral response for photodetection applications within the mid-IR region of the spectrum and enhances the performance of MOSFETs. This gives GeSn nanocompounds the chance to contribute greatly to IoT physical devices and compete with unstable perovskite materials since GeSn materials can achieve a stable and more reliable performance.

Fabrication of Nanocrystalline Silicon Thin Films Utilized for Optoelectronic Devices Prepared by Thermal Vacuum Evaporation.

Metal-induced crystallization of amorphous silicon is a promising technique for developing high-quality and cheap optoelectronic devices. Many attempts tried to enhance the crystal growth of polycrystalline silicon via aluminum-induced crystallization at different annealing times and temperatures. In this research, thin films of aluminum/silicon (Al/Si) and aluminum/silicon/tin (Al/Si/Sn) layers were fabricated using the thermal evaporation technique with a designed wire tungsten boat. MIC of a:Si was detected at annealing temperature of 500 °C using X-ray diffraction, Raman spectroscopy, and field emission scanning electron microscopy. The crystallinity of the films is enhanced by increasing the annealing time. In the three-layer thin films, MIC occurs because of the existence of both Al and Sn metals forming highly oriented (111) silicon. Nanocrystalline silicon with dimensions ranged from 5 to 300 nm is produced depending on the structure and time duration. Low surface reflection and the variation of the optical energy gap were detected using UV-vis spectroscopy. Higher conductivities of Al/Si/Sn films than Al/Si films were observed because of the presence of both metals. Highly rectifying ideal diode manufactured from Al/Si/Sn on the FTO layer annealed for 24 h indicates that this device has a great opportunity for the optoelectronic device applications.