This study explores the application of Polycarbosilane (PCS) as an intermediate adhesive bonding technique for 4H-SiC substrates aiming to overcome the challenges of producing high-quality and cost-effective substrates for high-power electronics. Thin layers of PCS mixed with m-xylene and AIBN (azobisisobutyronitrile) were deposited onto 4H-SiC substrates via a spin coating. For demonstration purposes, these coated 4H-SiC substrates were then bonded with another 4H-SiC substrate. A defect-free, high-temperature stable bond is facilitated by annealing at high temperatures. Effusion measurements were conducted to characterise the PCS thin films and examine the organic-inorganic transitions and the resulting outgassing at high temperatures. SEM analysis confirmed the uniformity of the bonded layer. These results demonstrate PCS’s potential in high-temperature applications and will stimulate further …

The study investigates the performance of Schottky barrier diodes (SBDs) fabricated on high-quality Sn-doped  -gallium oxide (Ga2O3) film on sapphire (0006) substrate. Temperature-dependent performances are probed, in terms of forward and reverse bias characteristics. When temperature increases from 25 °C to 200 °C, the barrier height increases, and the ideality factor advances to unity. The current conduction happens differently at low and high temperatures because of the inhomogeneity in Schottky barrier height. Different methods are used to analyze temperature variations in the barrier heights. A high breakdown voltage of >200 V at 25 °C and a decent  ratio for the all-temperature range are measured. The leakage current of the device does not significantly change with the temperature. These characteristics make the investigated Schottky diode structures on sapphire promising for future high …

Gallium oxide (Ga2O3) based phototransistor can be used as a switch and an amplifier in typical digital and analog UV photonic applications, respectively. The light detection capability in Ga 2 O 3 is very high, but these phototransistors suffer from poor drain current saturation with bias. Furthermore, the transistor switching action generally necessitates a gate terminal voltage, where a faulty gate power supply can lead to a high current flow in the transistor and subsequently damage the control driver circuit. An alternative is a two-terminal device with pure optical coupling at gate terminal, termed as a light effect transistor (LET). The LET has the field effect transistor (FET)-like current–voltage output characteristics, where the controlling mode is light instead of voltage, and being a two-terminal device, the fabrication processes are straightforward and cost-effective in contrast to the traditional FET.

Cu2ZnSnS4 (CZTS) absorber materials are often associated with high non-radiative recombination and band tailing which results in poor material properties. Herein, we successfully employ a small molecule, triethanolamine, to passivate the charged point defects and dangling bonds not only on the CZTS surface but also within the CZTS absorber. The Urbach energy of treated CZTS absorber reduced by 0.29 eV besides increased bandgap value unraveled the passivation of band-edge tail states. The band-to-band transitions (~ 6 times) enhanced over band-to-tail transitions in PL spectra after the treatment representing the significant suppression of non-radiative recombination. Our studies reveal that due to passivation of CZTS surface, the interface trap density was substantially reduced, influencing charge carrier dynamics of CZTS/TiO2 heterojunction-based devices. This work provides an insight toward the …

The greatest challenge for further improving the efficiency of Cu2ZnSnS4 (CZTS) solar cells is the high open-circuit voltage (VOC) loss owing to nonradiation interface recombination. Controlling interfacial defect states and hence eliminating interface-dominated recombination are imperative for device performance to achieve better charge extraction and collection. In this aspect, interface passivation is an effective way to resolve this issue. An ultrawide-bandgap Ga2O3 film is inserted between CZTS absorber and TiO2 electron transport layer to passivate the electrically active interface trap states. The induced field-effect passivation due to the existence of an additional field of Ga2O3 interlayer widens the depletion region width and cures the interfacial defect density. The significant photoluminescence quenching observed after inserting Ga2O3 at the CZTS/TiO2 heterojunction implies the effective injection of charge carriers from the CZTS absorber to TiO2 layer owing to reduced interface defect density. Meanwhile, the substantial decrement in dark current and response time of device with passivated interface further advocates the findings. Herein, a route to understand the variation in interfacial electrical properties after inserting a thin dielectric layer at the interface is provided, which can be beneficial for the further study of CZTS-based optoelectronic device applications.

The harmful UV radiation leaking out of the ozone hole can have a detrimental effect on mother nature. To monitor any UV rays leaking out of the ozone hole requires an electronic device such as deep UV photodetectors. In this context, Sn-doped Ga2O3 incorporated with SnO2 nanostructures has been grown on a c-plane sapphire substrate using low-pressure chemical vapor deposition (LPCVD) followed by the fabrication of metal-semiconductor-metal (MSM) based deep ultraviolet (UV) photodetector (PD) using Pt as electrodes with interdigitated geometry. The PD possesses a low dark current of 21 nA even at 50 V bias with a very high photo-to-dark current ratio of 9 × 104 and exceptionally large responsivity of 1532 and 262 A/W under 254 nm and 302 nm UV-illumination respectively. Consequently, an extremely high detectivity of 1.7 × 1015 Jones and external quantum efficiency of 7.4 × 105% has been recorded under 254 nm illumination with a fast fall time of 0.2 sec. The PD works well in UV-B range with high responsivity and is attributed to the long wavelength absorption by the SnO2 nanostructures accompanied by a charge transfer from SnO2 to the Ga2O3 layer. The high gain has been attributed to the photoconductive gain due to interface trapped charges and self-trapped holes, along with light trapping on the textured Ga2O3 surface.

Gallium Oxide (Ga2O3) is an emerging semiconductor for next-generation power electronics. Ga2O3 has been used as a substrate to deposit Ga2O3 thin film in most of the previously reported works. However, Ga2O3 substrate is costly which makes the technology too expensive. Thus, the cost-effective integration of Ga2O3 with the existing silicon technology is the primary motivation for the present research. In this context, the β-Ga2O3 film has been deposited on Si (10 0) substrate using pulsed laser deposition. XRD pattern of the deposited film shows the single crystalline nature with β-phase of Ga2O3. FESEM results confirm the film surface is smooth and uniform. Fabricated Schottky barrier diodes (SBDs) show good device performance with significantly high breakdown voltage and low ideality factor. Baliga’s Figure of merit (V2BR/RON) has been computed to be 0.021 MWcm-2. The present research has evaluated the feasibility of cost-effective integration of β-Ga2O3 with well-established technology Si and it would provide a new research opportunity of β-Ga2O3 on Si with potential commercial applications as well as challenges to overcome for high-performance power devices soon.

Gallium Oxide (Ga2O3) and Sapphire have been a preferred choice of substrates for fabricating β -Ga2O3 Schottky barrier diodes (SBDs). However, Si (100) substrate with low cost and relatively high thermal conductivity has been explored as a platform in this work for the growth of β -Ga2O3 using the pulsed laser deposition (PLD) technique. X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM) results confirm the good crystalline quality and uniformity of the Ga2O3 film, respectively. The roughness (RMS) of 1.44 nm of the film surface is confirmed by the atomic force microscope (AFM) technique. The current-voltage (I-V) and capacitance-voltage (C-V) characteristics are employed for investigating the electrical and interface trap properties of the SBDs. The Schottky barrier height measured at room temperature from I-V and C-V characteristics are 0.78 eV and 1.17 eV, respectively and the ideality factor turns out to be 1.95. The charge transport mechanism of SBD has been investigated using the log-log plot of I-V characteristics. The Schottky metal (Au)/ β -Ga2O3 interface trap density ( Dit ) is obtained on the order of ∼109 cm−2 eV−1 using the conventional conductance method. In the energy range of Ec -0.27 eV to Ec -1.57 eV, the density of interface states changes from 3.72×109 eV−1cm−2 to 3.10×109 eV−1cm−2, respectively. The maximum value of Dit is found to be 4.38×109 eV−1cm−2 at Ec -0.68 eV. The value of Dit can be further reduced for potential and reliable integration of β -Ga2O3 with Si electronics.

Vitreous or vitreous humor is a complex transparent gel that fills the space between the lens and retina of an eye and acts as a transparent medium that allows light to pass through it to reach the photoreceptor layer (retina) of the eye. The vitreous humor is removed in ocular surgery (vitrectomy) for pathologies like retinal detachment, macular hole, diabetes‐related vitreous hemorrhage detachment, and ocular trauma. Since the vitreous is not actively regenerated or replenished, there is a need for a vitreous substitute to fill the vitreous cavity to provide a temporary or permanent tamponade to the retina following some vitreoretinal surgeries. An ideal vitreous substitute could probably be left inside the eye forever. The vitreous humor is transparent, biocompatible, viscoelastic and highly hydrophilic; polymeric hydrogels with these properties can be a potential candidate to be used as vitreous substitutes. To meet the …

Sapphire and gallium oxide have been used as substrates for most of the reported results on β-Ga2O3 devices. However, silicon (Si) is an abundant material on the Earth, leading to easier and low-cost availability of this substrate, along with higher thermal conductivity, which makes Si a promising and potential substrate candidate for rapid commercialization. Therefore, in order to strengthen the feasibility of Ga2O3 on Si integration technology, we have deposited β-Ga2O3 on (100) and (111) oriented p-Si substrates using a pulsed laser deposition technique. A single-phase (β) and polycrystalline nature of the β-Ga2O3 film is observed for both samples using x-ray diffraction. A low root mean square roughness of 3.62 nm has been measured for Ga2O3/Si(100), as compared to 5.43 nm of Ga2O3/Si(111) using atomic force microscope. Moreover, Ga2O3/Si(100) shows a smoother and uniform surface of the Ga2O3 film, whereas Ga2O3/Si(111) seems to have a rougher surface with pitlike defects. This might be due to the hexagonal projection of Si (111) that is not suitable for obtaining a good tilted cuboid or monoclinic Ga2O3 crystal unlike the rectangle projection of Si (100). The electrical parameters of the fabricated Schottky barrier diodes were extracted using current–voltage (I–V) and capacitance–voltage (C–V) characteristics. The polycrystalline Ga2O3 film on Si(100) leads to fewer defects emerging from the Ga2O3/Si heterointerface due to the close symmetry of Ga2O3 and the Si(100) crystal with rectangle projections unlike Ga2O3 on Si(111). These fewer defects eventually lead to a better diode performance of Ga2O3/Si(100) where we have observed typical thermionic dominating carrier transport, whereas defect-assisted thermionic field emission has been the primary carrier transport mechanism in Ga2O3/Si(111). Hence, the Si (100) substrate is demonstrated to be a better and potential platform for Ga2O3 devices than Si (111).

Earth abundant CZTS (Cu 2 ZnSnS 4) absorber layers are promising for the development of cost-effective and large area photovoltaics; however, interfacial nonradiative recombination is a major obstruction to the pathways toward high performing CZTS devices. Elimination of interfacial recombination losses via interface engineering is paramount to obtain efficient CZTS solar cells. Herein, we report a systematic investigation of the influence of oxygen vacancies (O V) settled at the CZTS/TiO 2 interface on the charge transfer rate in heterostructures. Modulation of O V by varying oxygen flow rate during TiO 2 deposition was confirmed by x-ray photoelectron spectroscopy. Lower O V concentration shifted the conduction band offset from negative to positive at the CZTS/TiO 2 heterojunction, which is essential for efficient charge transportation through the interface. Photoluminescence quenching of the CZTS/TiO 2 …

Highly crystalline β-Ga2O3 has been grown on a c-plane (0001) sapphire substrate using low-pressure chemical vapor deposition. This work has been focused on the impacts of the Gallium (Ga) concentration on the surface morphology of the β-Ga2O3 films. Formation of thin film, nanostructure, and the combination of both have been observed. However, no changes have been noticed on the X-ray diffraction peaks of β-phase with an increase in Ga vapor concentration, though different crystal orientation of the nanostructures has been found in the sample with relatively high Ga amount. The average crystallite size which has been calculated using Scherrer's formula shows an increment with Ga concentration. The bandgap has also been found to be altered with the metal concentration. The crystal quality of the nanostrctures evaluated from the Raman measurements shows good quality with low internal strain and …

In this article, β-Ga2O3 film was deposited on the p-Si (100) substrate using pulsed laser deposition (PLD) technique for rapidly emerging Ga2O3-based Schottky barrier diodes (SBDs). Although X-ray diffraction (XRD) result reveals a polycrystalline trending film, a smooth and uniform as-grown surface has been characterized by atomic force microscope (AFM) and field-emission scanning electron microscope (FESEM). Further, we have investigated metal–semiconductor (M–S) contact behavior of the fully vertical SBDs with the four different metals such as aluminum (Al), silver (Ag), gold (Au), and platinum (Pt) on Ga2O3 after forming ohmic contacts on the backside of the Si substrate. The barrier heights of all four metals are typically in the range of 0.51–0.69 eV and 0.72–1.41 eV as obtained from the current–voltage (I–V) and capacitance–voltage (C–V) characteristics, respectively. The carrier concentration is …

Schottky barrier diodes (SBDs) have been fabricated laterally on a β-Ga 2 O 3 film grown on both p-type and n-type Si (100) substrates using a pulsed laser deposition technique. The sample of Ga 2 O 3 on p-Si was further annealed at 600 C to optimize device performance. Platinum (Pt) and Titanium (Ti)/Gold (Au) metal stacks have been utilized for the formation of Schottky and Ohmic contact on the Ga 2 O 3, respectively. Considerably high breakdown voltages (V BR) of 190, and 172 V and a significantly low on-resistance (R on) of 330, and 15 mΩ. cm 2, have been obtained for the as-deposited sample and sample annealed at 600 C, respectively for lateral Ga 2 O 3/p-Si SBDs. Moreover, a much lower V BR of 56 V and higher on-resistance of 970 mΩ. cm 2 have been measured for Ga 2 O 3/n-Si SBDs as compared to the Ga 2 O 3/p-Si. The presence of REduced SURface Field effect in n-Ga 2 O 3/p-Si based …

A unique metal–semiconductor–metal (MSM) photodetector has been fabricated using Sn incorporation in Ga 2 O 3 forming Sn x Ga 1-x O nanostructures (Ns) with platinum (Pt) metal as contacts. The mixed nanostructures (MNs) has been attributed to an increment in the detection range of UV (254–302 nm) with ultra-low dark current, hence a potential device in the field of long range deep-UV detector. Sn x Ga 1-x O Ns are deposited on c-plane sapphire using low-pressure chemical vapour deposition. From the x-ray diffraction (XRD) results, existence of both Sn x Ga 1-x O and tetragonal SnO 2 MNs are confirmed. The XRD peak shifts in Sn x Ga 1-x O are attributed to the integration of Sn with Ga forming a Sn x Ga 1-x O alloy with x to be∼ 7.3% determined from the Vegard's law. The field effect scanning eletron microscope images show the thick diameter wire-shaped nanostructures. The absorption spectra show …

Cost-effective integration with existing silicon CMOS electronics has been one of the primary motivations for most of the emerging non-silicon devices. In this context, β-gallium oxide (Ga2O3) films were deposited on Si (100) substrate using pulsed laser deposition (PLD) technique in this research. After deposition, samples were further annealed at 600 °C and 800 °C under vacuum. X-ray diffractometer (XRD) was employed to observe the crystallinity variation due to the annealing. The crystallinity of samples degrades with annealing at 600 °C and an incremental improvement in crystallinity was again exhibited at 800 °C due to the possible rearrangement of the Ga and O atoms to their optimal sites. Further, x-ray photoelectron spectroscopy (XPS) was used for identification of elements and chemical composition. XPS results were also analyzed to locate the position of Ga 2p and Si 2p core levels and calculate the …

Analytical modeling with a verified simulation setup of surface potential, threshold voltage and electric field for a 4H-SiC MOSFET is presented to make enquiries about the short channel effects. The two-dimensional (2D) Poisson equation is used to achieve the model for surface potential. The 2D position equations have been solved by using four boundary conditions. The detail of the model is appraised by the various MOSFET parameters such as silicon carbide thickness, body doping concentration, and gate oxide influencing the electric field, channel potential and threshold voltage. The outcome shows that this model can reduce the short channel effects, drain induced barrier lowering and advance the sub-threshold fulfillment in nanoelectronic applications as compared to silicon MOSFETs. By comparing the model results with the 2D device simulations the veracity of the suggested 2D analytical model is proven.