Valence-State Controllable Fabrication of Cu_2–xO/Si Type-II Heterojunction for High-Performance Photodetectors

Abstract

Cuprite, nominally cuprous oxide (Cu2O) but more correctly Cu2–x O, is widely used in optoelectronic applications because of its natural p-type, nontoxicity, and abundant availability. However, the photoresponsivity of Cu2O/Si photodetectors (PDs) has been limited by the lack of high-quality Cu2–x O films. Herein, we report a facile room-temperature solution method to prepare high-quality Cu2–x O films with controllable x value which were used as hole selective transport layers in crystalline n-type silicon-based heterojunction PDs. The detection performance of Cu2–x O/Si PDs exhibits a remarkable improvement via reducing the x value, resulting in the optimized PDs with high responsivity of 417 mA W–1 and fast response speed of 1.3 μs. Furthermore, the performance of the heterojunction PDs can be further improved by designing the pyramidal silicon structure, with enhanced responsivity of 600 mA W–1 and response speed of 600 ns. The superior photodetecting performance of Cu2–x O/n-Si heterojunctions is attributed to (i) the matched energy level band alignment, (ii) the low trap states in high-quality Cu2O thin films, and (iii) the excellent light trapping. We expect that the low-cost, highly efficient solution process would be of great convenience for large-scale fabrication of the Cu2–x O thin films and broaden the applications of Cu2–x O-based optoelectronic devices.

Underwater Multispectral Computational Imaging Based on a Broadband Water-Resistant Sb2Se3 Heterojunction Photodetector

“…To further enhance the weak-light capability of our underwater imaging system, we further constructed a CdS/Sb 2 Se 3 heterojunction by a simple chemical bath deposition to improve the photodetection performance of PDs. The heterojunction, as a general strategy that improves the performance of optoelectronic devices, enables the construction of built-in electric fields for promoting separation of photocarriers and reducing carrier recombination. − The fabricated CdS/Sb 2 Se 3 heterojunction PD exhibits excellent photodetection performance, including self-powered characteristic, high responsivity of 0.47 A/W at zero bias, ultrahigh on/off ratio of over 10 7 , and wide linear dynamic range of 128 dB. Moreover, we introduce advanced Fourier imaging algorithms in our underwater imaging system for improving the imaging quality and imaging repeatability.…”

Epitaxial Electrodeposition of Optically Transparent Hole-Conducting CuI on n-Si(111)

“…The deviation from unity for the diode quality factor suggests a mixture of carrier diffusion and the recombination mechanism at the p-CuI/SiO x /n-Si interface . The diode quality factor reported for similar CuI-based heterojunction diodes with less ordered CuI is relatively higher, revealing a high-quality heterojunction formed through electrodeposition. , A better diode quality factor indicates a suppressed carrier recombination at the surface and in the space-charge layer in the case of epitaxial films …”

“…29 The diode quality factor reported for similar CuI-based heterojunction diodes with less ordered CuI is relatively higher, revealing a high-quality heterojunction formed through electrodeposition. 30,31 A better diode quality factor indicates a suppressed carrier recombination at the surface and in the space-charge layer in the case of epitaxial films. 32 The interfacial energetics was determined from the J−V plot at forward bias using eq 4, 32 where A* is the effective Richardson's constant (120 A cm −2 K −2 for n-Si), k is Boltzmann's constant (1.38 × 10 −23 J K −1 ), T is the temperature (298 K), q is the charge of an electron (1.60 × 10 −19 C), and J 0 is the dark saturation current density (A cm −2 ).…”

Spectrum-shaped Si-perovskite hybrid photodetectors for hyperspectral bioimaging

“…However, the spectral responsivity of silicon has enormous difference in all spectral ranges, i.e., the optimal responsivity is at the NIR region due to the nature of the indirect bandgap in silicon of around 1.1 eV [20]. Its responsivity in the visible region is inferior and unbalanced (falls off monotonously with decreasing wavelength [21][22][23]), which is not suitable for high-performance visible HSI. That is, conventional Si-CCDs exhibit poor responsivity at short wavelengths (e.g., 400-600 nm) compared with that at longer wavelengths.…”