AlInSb Mid‐Infrared LEDs of High Luminous Efficiency for Gas Sensors

Abstract

In this paper, performance of mid-infrared light emitting diodes (LEDs) with an InSb buffer layer and AlInSb active/barrier layers, emitting at room temperature is reported. This film structure makes an ideal base material in view of carrier confinement and crystalline quality. In order to achieve a high efficiency for light extraction, backside emission architecture is adopted together with a rough emitting surface and TiO 2 anti-reflection coating. The resulting AlInSb LED shows 75% higher power conversion efficiency than the reference, which has the highest efficiency in the market to date.

Towards Integrated Mid-Infrared Gas Sensors

“…For example, despite the success of QCLs in the MIR [37,38], their high-cost (∼$1000) and high-power consumption have limited their application to consumer electronics. MIR LEDs can offer lower power consumption with overall high efficiencies [39,40], however, their operation above ∼5 μm is challenging [45] and comes at significantly increased costs (∼$100). Nevertheless, renewed scientific interest in the miniaturization of low-cost optical gas sensors [43,54,63], is being fueled by advances in silicon micromachining [36,87].…”

“…In addition, dedicated filtering and detection mechanisms are needed [3]. Development of new light sources (e.g., quantum cascade lasers (QCLs) [37,38], light emitting diodes (LEDs) [39,40], and micro-electro-mechanical systems (MEMS)-based thermal emitters [41,42,43]), and detection techniques (e.g., optical [3], and acoustic [44]) have changed the outlook of optical gas sensors over the past two decades. These advancements, in particular the realization of new MIR sources [45], combined with the increasing needs to develop new innovative technologies for healthcare, digital services and other innovation [46], are driving optical gas sensors towards low-cost, mainstream applications [15,19].…”

“…Photoacoustic sensors, using highly-sensitive MEMS microphones, have also emerged as compact, low-cost sensors with high sensitivity and stable operation [44,50,51]. Nevertheless, current optical gas sensing technologies still suffer from drawbacks, e.g., QCLs are expensive complex heterostructures [37,38], LEDs have limited emission for λ > 5 μm [39], and MEMS micro-heaters suffer from poor emissivity [52]. In addition, long (∼cm [3]) optical interaction pathlengths are required to increase the sensor signal response.…”

Mid-infrared resonant cavity light emitting diodes operating at 4.5 µm

“…There has also been significant interest in developing mid-infrared LEDs on less expensive GaAs substrates, using various buffer layer schemes to accommodate the large inherent lattice mismatch with respect to active regions of alloys and heterostructures having suitable band gaps [7]. This resulted in devices of some complexity ranging from LEDs with bulk active regions in small arrays [8][9][10][11], to multispectral mid-infrared multiple quantum well (MQW) emitters [12]. Sources with sufficiently narrow linewidth and high enough spectral intensity could also be integrated with Si/Ge waveguides [13][14][15][16].…”

Highdetectivity AlInSb Midinfrared Photodiode Sensors with Dislocation Filter Layers for Gas Sensing

“…To develop a high‐resolution NDIR gas sensor with low power consumption, we need a high‐efficiency light‐emitting diode (LED) and a high‐sensitivity photodiode. We have already developed a midinfrared LED for gas sensing and the photodiode for human detecting . The LED for detecting CH 4 contained dislocation filter layers (DFLs) to reduce the dislocation density in the active layer, which increased the luminous efficiency drastically …”