Research On Novel Ga As Based Short Wavelength Infrared Photodetector

Infrared radiation is a large number of signals and energy in nature,but it can not be perceived by human eyes.Infrared detection is an extremely important weapon for human to understand the nature,which can expand human vision and explore the unknown world.After more than a hundred years of development,infrared detector technology has expanded from the initial national defense and military fields to civil equipment,which plays an important role in social life,production and scientific research.In recent years,photonic infrared detectors based on semiconductor materials have made outstanding contributions in remote sensing,imaging,optical communication and many other fields with their high sensitivity and high response speed.However,in the 1.1?m short wave infrared range,there is no detector with good wavelength limit matching.The dark current suppression of existing In Ga As detectors is still not perfect,and the wavelength limit of Si based detectors is difficult to extend to this wavelength.Therefore,it is of great significance to study a new type short wave infrared detector which can take into account both wavelength expansion and dark current suppression.In our previous experiments,we found that the depletion region of p-i-n structure has an enhanced optical absorption.On the basis of this result,several Ga As based p-i-n structure materials were designed and fabricated.After detailed experimental test and comparison,the phenomenon of enhanced optical absorption was reproduced.The transient transport process of photogenerated carriers in the materials was observed by femtosecond transient optical response test.In this paper,the above experimental results are discussed and analyzed in detail,which provides a substantial theoretical explanation for the phenomenon of enhanced optical absorption,and provides a theoretical basis for the subsequent design of infrared detector.In addition,we also found the efficient escape of localized photogenerated carriers in p-n junctions in In Ga As,In Ga N,In As and other materials.According to the enhancement of optical absorption and efficient carrier escape,we have designed and fabricated a large strain In Ga As/Ga As interband quantum well infrared detector,and completed the fabrication of the prototype device and related performance tests.In this structure,the barrier material with larger band gap can effectively suppress the dark current of the device,while the well material with smaller band gap can realize the wavelength expansion.The optical absorption enhancement and efficient carrier escape ensure that the design structure has good photoelectric response ability even though the active region is very thin.In order to solve the problem of lattice mismatch between high component In Ga As and Ga As,we optimized the MBE process and determined the optimal growth temperature of 485?.Based on the optimized growth parameters,we have fabricated In Ga As/Ga As interband quantum well infrared detectors with 20 periods of large strain on p-type Ga As substrate,and further completed the prototype of 1×15 element linear array device.After a series of performance characterization and parameter testing,without the subsequent antireflection film evaporation and device packaging,the wavelength of the detector is successfully extended to 1070 nm,and the dark current density is suppressed to 4.2×10⁸ A/cm² at-0.1 V bias,and the peak D-star is 8.6×10¹¹Jones(cm·Hz^1/2/W).After the prototype of infrared detector is prepared by using the novel Ga As structure,in order to further explore its practical application capability,we have developed a single integrated active near infrared detection system which can complete the optical emission and light detection at the same time by processing on the 940 nm band LED epitaxial wafer with similar structure.The performance of the system shows that the detector can detect the smooth surface objects within 5 cm.The results have great potential in the application of light proximity sensors,and also verify the capability of the new Ga As based detector.These experimental results verify the enhancement effect of light absorption and the high efficiency escape of localized carriers,which is of guiding significance for the new structure design of the short wave infrared optoelectronic detector.