High-performance MoO _x /n-Si heterojunction NIR photodetector with aluminum oxide as a tunneling passivation interlayer

Abstract

The most effective and potential approach to improve the performance of heterojunction photodetectors is to obtain favorable interfacial passivation by adding an insertion layer. In this paper, MoO x /Al2O3/n-Si heterojunction photodetectors with excellent photocurrents, responsivity and detectivity were fabricated, in which alumina acts as a tunneling passivation layer. By optimizing the post-annealing treatment temperature of the MoO x and the thickness of the ultra-thin Al2O3, the photodetector achieved a ratio of photocurrent to dark current of 3.1 × 105, a photoresponsivity of 7.11 A W−1 (@980 nm) and a detective of 9.85 × 1012 Jones at −5 V bias. Besides, a self-driven response of 0.17 A W−1 and a high photocurrent/dark current ratio of 2.07 × 104 were obtained. The result demonstrated that optimizing the interface of heterojunctions is a promising way to obtain a heterojunction photodetector with high-performance.

Enhanced performance of a n-Si/p-GaTe heterojunction through interfacial passivation and thermal oxidation

“…Similar behavior of an enhanced photoresponse by the AlO x passivation layer has been reported in other optoelectronic devices. 28–31 In addition, the photocurrent of the n-Si/p-GaTe heterojunction without the AlO x layer is also increased by the same thermal oxidation process, as shown in Fig. S4 (ESI†), which is attributed to the thermal oxidation of GaTe.…”

“…The interface quality of heterojunctions plays an important role in the overall electronic and optoelectronic performance. 25,26 AlO x as a passivation layer has been demonstrated to be effective for enhanced photovoltaics, [27][28][29][30][31] which not only reduces the interface recombination induced by surface states and interlayer tunneling but also allows carriers to transport through the interface by tunneling. The doping also can enhance the optoelectronic performance by modulating the band structure of semiconductors to enlarge the built-in electric field.…”

Self-Powered and Fast Response MoO3/n-Si Photodetectors on Flexible Silicon Substrates with Light-Trapping Structures

“…It indicates the MoO 3 film is only composed of the hexagonal phase, representing excellent crystallinity. According to our previous work, − the excellent interfacial passivation properties of ALD-deposited ultrathin Al 2 O 3 tunneling layers can improve the performance of PDs. In this work, the tunneling and passivation layer was also adopted in our FPDs.…”

Interfacial Engineering with Aluminum Oxide toward an Improved Self‐Powered Narrowband Visible‐Light Photodetection in Lead Halide Perovskite CH3NH3PbBr3/p‐Si Heterojunctions

“…However, high‐density interface trap states, which are generally originated from undercoordinated atoms (i.e., dangling bonds), have been widely observed within the heterojunction devices. [ 18–20 ] Notably, the interface trap states are detrimental to the conversion efficiency of light‐to‐electric, which greatly decrease the performance of resulting PDs. Briefly, the interface trap states can greatly reduce the average lifetime of photogenerated charge carriers via interface recombination (i.e., recombination loss) [ 21 ] and therefore reduce the overall self‐powered photoconductive gain.…”

“…We attribute it to the effective passivation (reduction) of heterojunction interface trap states by the Al 2 O 3 thin interlayer, which suppressed the generation of electrons and holes within the reverse‐biased space charge region, as schematically shown in Figure 2b (bottom panel). In addition, the forward‐biased current density (≈1.4 µA cm −2 ) in the MAPbBr 3 /Al 2 O 3 /p‐Si heterojunction PD is slightly reduced, which is caused by the barrier effects of Al 2 O 3 on charge carriers’ transportation, [ 20 ] as shown in Figure 2a, but comparable to the MAPbBr 3 /p‐Si heterojunction PD (≈2.0 µA cm −2 ). This suggests the effective tunneling of charge carriers while they passing through the Al 2 O 3 thin interlayer.…”