The spectral response of common optoelectronic photodetectors is restricted by a cutoff wavelength limit λ that is related to the activation energy (or bandgap) of the semiconductor structure (or material) (Δ) through the relationship λ = hc/Δ. This spectral rule dominates device design and intrinsically limits the long-wavelength response of a semiconductor photodetector. Here, we report a new, long-wavelength photodetection principle based on a hot-cold hole energy transfer mechanism that overcomes this spectral limit. Hot carriers injected into a semiconductor structure interact with cold carriers and excite them to higher energy states. This enables a very long-wavelength infrared response. In our experiments, we observe a response up to 55 μm, which is tunable by varying the degree of hot-hole injection, for a GaAs/AlGaAs sample with Δ = 0.32 eV (equivalent to 3.9 μm in wavelength).
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机译:普通光电探测器的光谱响应受截止波长极限λ的限制,该极限波长与λ= hc /Δ的关系与半导体结构(或材料)(Δ)的激活能(或带隙)有关。该光谱规则支配了器件设计,并固有地限制了半导体光电探测器的长波长响应。在这里,我们报告了一种新的长波长光电检测原理,该原理基于克服了这种光谱限制的热冷空穴能量传输机制。注入到半导体结构中的热载流子与冷载流子相互作用并使它们激发到更高的能量状态。这实现了非常长波长的红外响应。在我们的实验中,对于Δ= 0.32 eV(相当于波长3.9μm)的GaAs / AlGaAs样品,我们观察到高达55μm的响应,该响应可通过改变热空穴注入的程度来调节。
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