In this paper, the formation of dark spot defects (DSD's) in InP/InGaAsP LED's is studied by cathodoluminescence (CL) imaging, electron-beam-induced-current (EBIC) imaging, Auger electron spectroscopy (AES), and energy dispersive X-ray spectroscopy (EDS). Defects resulting in DSD's are shown by CL and EBIC to be located in either the p-InGaAsP contact layer or the p-InP confining layer for short aging times. For longer aging times, these defects are also found in the InGaAsP active layer. The presence of gold was not detected at the DSD's using EDS. However, gold was found in the form of submicron size inclusions at the contact layer-confining layer interface of cylindrically-lapped wafers using AES and EDS. Our results strongly suggest that the migration of gold from the p-contact during device processing and aging results in the formation of DSD's in InP/InGaAsP LED's.
An impressive technology now exists for the fabrication of photodetectors based on InGaAsP/InP heteroepitaxy. Excellent performance is obtained over the range from 1.0 pm to 1.7 gm, making these devices ideal for optical fiber communication applications. In this paper, we will review the state-of-the-art of InP based photodetectors with emphasis on their reliability. We will discuss some of the known failure mechanisms and describe measures taken to eliminate them. We will show results of reliability experiments performed in our laboratories on photodetectors. These devices have demonstrated extrapolated failure rates below 1 FIT and are now used in submarine cable systems and other applications with demanding reliability requirements.
With use of low-energy ${\mathrm{Ne}}^{+}$ scattering and low-energy electron diffraction both long-range order and Au segregation have been found at the ${\mathrm{Cu}}_{3}$Au(001) surface. The Au concentrations in the first and second layers are essentially constant at 0.5 and 0, respectively, for $T<~400\ifmmode^\circ\else\textdegree\fi{}$C, beyond which they approach each other. Calculations of shadowing for the ordered surface agree with experiment, e.g., for shadowing of Cu atoms in the second and third layers by Au atoms in the first layer.
