This paper presents three self-powered photodetectors namely, p ⁺ -bilayer graphene (BLG)/n ⁺ -ZnO nanowires (NWs), p ⁺ -BLG/n ⁺ -Si NWs/p ^– -Si and p ⁺ -BLG/n ⁺ -ZnO NWs/p ^– -Si. The Silvaco Atlas TCAD software is utilized to characterize the optoelectronic properties of all the devices and is validated by analytical modeling. The proposed dual-junction photodetectors cover broadband spectral response varying from ultraviolet to near-infrared wavelengths. The dual-heterojunction broadband photodetector exhibits photocurrent switching with the rise and fall time of 1.48 and 1.27 ns, respectively. At −0.5 V bias, the highest external quantum efficiency, photocurrent responsivity, specific detectivity, and the lowest noise equivalent power of 71%, 0.28 A W ⁻¹ , 4.2 × 10 ¹² cmHz ^1/2 W ⁻¹ , and 2.59 × 10 ^–17 W, respectively, are found for the dual-heterojunction device with a wavelength of 480 nm at 300 K. The proposed nanowires based photodetectors offer great potential to be utilized as next-generation optoelectronic devices.

In this study, the authors present three different metamaterial absorbers (MMAs) namely, T, split‐I (SI) and split‐Jerusalem cross (SJC) with different dimensions and geometrical configurations. The absorption rates of T‐, SI‐ and SJC‐shaped absorbers are studied at microwave frequencies. T‐shaped absorber demonstrates perfect absorption at 10.19 GHz, making it suitable for single band operation, whereas SI‐shaped absorber exhibits two perfect absorption peaks at 9.32 and 10.75 GHz finding its application in dual band operation. However, novel SJC‐shaped absorber demonstrates multiple absorption peaks at 9.92, 10.42, 10.93, 11.75 and 13.25 GHz with absorption of 99.5, 91, 99.9, 91.8 and 99.6%, respectively, making it suitable for X‐ and Ku‐band operations. The proposed MMAs have a thickness of around 0.8 mm (i.e. < λ /37) with respect to the lowest frequency of operation. Furthermore, the absorbers are analysed for different angles of polarisation and incidence for transverse electric polarised wave with a step size of 15°. The proposed absorbers have been fabricated and experimentally demonstrated at X‐band verifying the results obtained from simulations and implementing an equivalent circuit method. Further, SJC‐shaped absorber is demonstrated for multi‐and wide‐band terahertz applications exhibiting four perfect absorption peaks at 2.76, 2.89, 3.02 and 3.31 THz.

We present novel p ⁺ -bilayer graphene (BLG) and mercury cadmium telluride (MCT)-based single- and dual-junction photodetectors, namely, p ⁺ -BLG/n ^- -MCT and p ⁺ -BLG/n ^- -MCT/n ⁺ -MCT, operating in long infrared regime. The optoelectronic characterizations utilizing Silvaco Atlas TCAD are validated by analytical modeling. All the devices demonstrate self-powered mode operation and exhibit more than 10 ⁶ times enhancement in photocurrent density. The dual-heterojunction photodetector demonstrates rapid photocurrent switching with the rise and fall time of ~0.05 and ~0.013 ps, respectively, than that of single-heterojunction-based photodetectors. The highest external quantum efficiency (QE _ext ), external photocurrent responsivity, and lowest noise equivalent power of 85.8%, 7.33 A/W, and 4.72 × 10 ^-20 W, respectively, are found for the dual-heterojunction photodetector with a wavelength of 10.6 μm at 77 K. Such optimum photodetection performance is attributed to the presence of a huge amount of electric field (180 kV/cm) at n ^- -n ⁺ heterojunction, which accelerates the photogenerated electrons resulting in effective photocurrent. It is further demonstrated that the temperature-dependent QE _ext with values >100% is due to the carrier multiplication effect in BLG.

We present a high-performance bilayer graphene (BLG) and mercury cadmium telluride (Hg_1−xCd_x=0.1867Te) heterojunction based very long wavelength infrared (VLWIR) conductive photodetector.