The uncooled InGaAs-based infrared detector has received great interest in recent years for its application in optical-fiber
communication and remote sensing. However, the improvement of device performance is hampered by the lack of
feasible method to monitor its device process. The Microwave Photoconductivity Decay (μ-PCD) technique is a
contactless and non-destructive technique of the recombination lifetime characterization and mapping and has found
wide application in semiconductor research. In this paper, a double heterojunction p-i-n InP/In0.53Ga0.47As/InP mesa
structure was fabricated by Ar+ ion etching and the μ-PCD technique was applied to characterize the electrical effects of
ion etching on this structure. The results revealed that the built-in field in the p-n junction played a critical role in
recombination of photo induced minority carriers which made the mesa structure identifiable but not identical with the
lifetime mapping of the sample. The recombination lifetime in the mesa was dominated by the recombination process in
the edge of the mesa. The lifetime in the etched region was also influenced by the built-in field and increased with the
decrease of distance to the mesa area. And ion etching brought great nonuniformity to the photo active cells.
AlGaN is am important ultraviolet optoelectronic material and inductively coupled plasma (ICP) etching plays an
important role in fabrication of mesa structures of AlGaN-based photodiodes. In this work, we investigate ICP etching
processes of Al0.32Ga0.68N and Al0.47Ga0.53N. The Al0.32Ga0.68N and Al0.47Ga0.53N materials were firstly tested by
transmission spectra and it indicates that they are different materials with different epitaxial quality. Cl2/Ar/BCl3 were
used as the ICP gases, and Cl2/Ar mixing ratio was fixed at 4:1. Etching behaviors were characterized by varying the ICP
power, the dc bias, Cl2/Ar/BCl3 mixing ratio. ICP power influences etching rates. Dc bias heavily influences the etching
rates, and the etching rates increase monotonously with dc bias, which suggests that the ion-bombardment effect is an
important factor of these etching processes. BCl3 is the effective removal of oxygen during the etching, and also
influences etching rates. The surface rms roughness was measured by an at omic force microscope. The ICP etching
surface morphologies were studied by Scanning Electron Microscope (SEM). The results show dc bias and BCl3 are
important to electrical characteristics of epitaxial materials. At a relative high dc bias and more BCl3, the etching rate is
low, but the damage is low. These results have direct application to the fabrication of AlGaN-based ultraviolet
Gallium Nitride (GaN) UV detectors have become one of the most important UV detectors for much more compact, more robust, higher quantum efficiency and good stability in higher temperature environment than the traditional detectors. We can evaluate the quality of the detectors by detectivity, responsivity, Signal-to-Noise (the detector with read-out circuit), etc. Although these methods can analyze performance quantificationally, they are partial and indirect. The demo imaging system described in this paper provided a simple and more direct way as an assistant method. We can easily assess the performance of the detectors in actual application by the images obtained by the imaging systems. The system is mainly designed for 64x1 linear UV detectors (the band is 330nm ~ 365nm). It is composed of a precise scanner platform to provide 1-D wide field scan (it can be extended to 2-D if needed), UV telephoto optical system, signal transfers and processing system and the software. The detail design of these components is introduced. The images obtained by the system are also given at the end of the paper.
For the limit of its lifetime, the Stirling cooler is operated on the intermittent mode in satellite in some cases. Thus such cryogenic semiconductor components as HgCdTe mid or long wavelength infrared (IR) detectors are subjected to thousands of repeated thermal cycles from below -173°C to room temperature. Therefore, a series of experiments focused on quality, performance and reliability are essential in order to satisfy the reasonable requirements. Accordingly, a feasible thermal cycle screening system is put forward. And a vast experimental data show that thermal cycle tests play the most effective role in the environment stress screen (ESS).
In this paper, we introduce the system to help to study the main failure mechanisms and improve the performance of the semiconductor components. Such main failure mechanisms as solder-ball invalidation encountered commonly in the detector modules, which is due to the large thermal expansion coefficient mismatch among different materials.
The thermal cycle system is based on the principle of heat exchange. We expect HgCdTe IR detectors be cooled to lower than -173°C and heated to room temperature in a few minutes. Above all, we simulate the heating and cooling system through finite element method (FEM). As a result, the computations reveal that the IR detectors can be heated and cooled at a higher rate than expected. A consequent design of the entire system is founded on the simulation. At last, we adjust the mechanical structure of heat exchange system to the adaptive state to accomplish the ESS.
The thermal cycle screening system includes an autocontrol part and a test part. The autocontrol part is adopted to realize the heat exchange between IR detectors and the environment, and the test one to inspect the temperature and electrical parameters of these detectors. And at least four IR detector samples can be screened at one time.