M. A. DiGiuseppe

Optically induced catastrophic degradation in InGaAsP/InP layers

Laser‐induced catastrophic degradation in InGaAsP layers has been investigated. Catastrophic dark line (CDL) defects are generated at the spontaneous radiation flux in excess of 100 MW/cm2, significantly higher than in similar GaAlAs structures. In contrast to CDL’s in GaAlAs these dark lines are shown to be due to localized melting at material defects and not at cleaved mirror facets. In view of the very high power threshold this type of catastrophic degradation should be of limited importance for the InGaAsP lasers.

Quantum well structures of In0.53Ga0.47As/InP grown by hydride vapor phase epitaxy in a multiple chamber reactor

A computer controlled multiple chamber chemical vapor deposition reactor, designed for the growth of InP based alloys, has been constructed. In this system, specular epitaxial layers of InP and In0.53Ga0.47As are grown in separate chambers. This allows for the uninterrupted growth of In0.53Ga0.47As/InP quantum well structures with layer thicknesses of approximately 150 A. The photoluminescence spectra of these structures exhibit upward energy shifts as large as 71 meV from the band‐gap energy of In0.53Ga0.47As. Laser action at 1.5–1.6‐μm wavelengths has been obtained at temperatures up to 100 °C by optical pumping with a Q‐switched neodymium:yttrium aluminum garnet laser.

Cathodoluminescence evaluation of dark spot defects in InP/InGaAsP light‐emitting diodes

In this study, the formation of dark spot defects (DSD’s) in InP/InGaAsP light‐emitting diodes (LED’s) is evaluated by cathodoluminescence imaging and energy dispersive x‐ray spectroscopy (EDS). Defects resulting in DSD’s are shown to be located in either the p‐InGaAsP contact layer, the p‐InP confining layer, or 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‐sized inclusions in the contact layer and confining layer of cylindrically lapped wafers using 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.

Light‐current characteristics of InGaAsP light emitting diodes

Light‐current characteristics of 1.3‐μm InGaAsP light emitting diodes were investigated as a function of temperature between 70 and 350 K. The sublinearity of the light output found at high injection levels was shown to be temperature independent and similar in magnitude to that observed in GaAlAs devices. These experimental results cannot be explained with the previously proposed models of in‐plane superluminescence and Auger recombination.

Manifestations of melt‐carry‐over in InP and InGaAsP layers grown by liquid phase epitaxy

Macroscopic evidence for the occurrence of melt‐carry‐over (MCO) in InP and InGaAsP layers, grown by liquid phase epitaxy, is presented. It is shown that MCO can manifest itself in the form of dissolution pits and holes in epilayers. Further, this carry‐over can occur in any stage of epi growth and can propagate through subsequent epitaxial layers. Thus, holes transcending all four layers constituting a device wafer can form if wipe‐off after an In‐melt back is incomplete, and these holes have deleterious effects on device yield.

Degradation of 1.3‐μm InP/InGaAsP light‐emitting diodes with misfit dislocations

The degradation of 1.3‐μm InP/InGaAsP light‐emitting diodes (LED’s) with misfit dislocations was investigated. Initially, the misfit dislocations were found to be present only in the p‐InP confining layer and they thus showed weak (∼1%) contrast in the electroluminescence (EL) image of the light‐emitting region. Without bias, no degradation of the LED’s was measured after 103 h at 200 °C. After 103 h at 20 °C and 8 kA/cm2, a previous study found that InP/InGaAsP LED’s containing misfit dislocations did not degrade. However, our study showed that the lifetime of the LED’s varied inversely with the third power of the current density. In the degraded LED’s, the misfit dislocations showed stronger (∼50%) contrast in the EL image, suggesting that they played a significant role in the device degradation. In these devices, misfit dislocations were found not only in the p‐InP confining layer but also in the light‐emitting region of the active layer. The degradation of InP/InGaAsP LED’s with misfit dislocations is...

Growth of InGaAs structures using in situ electrochemically generated arsine

The use, transportation, and storage of the hazardous gas, arsine, raise serious safety issues. Consequently, there is considerable interest in the generation of arsine on demand from less hazardous substances. We report the first use of in situ generated arsine for III‐V epitaxy. The gas has been generated electrochemically at an arsenic cathode in an aqueous electrolyte and used to supply a hydride vapor phase epitaxy reactor. InGaAs/InP test structures were grown on InP substrates and were similar to comparison structures grown using tank arsine. Recessed‐gate enhanced Schottky metal‐semiconductor field‐effect transistors were fabricated and exhibited well‐behaved current‐voltage characteristics.

The effect of melt-carry-over on the LPE growth of planar buried InGaAsP/ InP double heterostructures

Abstract Liquid phase epitaxy (LPE) has been used to grow planar buried In 1- x Ga x As y P 1- y /InP double heterostructures. It is show n that poor wipe-off after melt-back and subsequent epitaxial growth over the mesa results in melt-carry-over on the surface and walls of the buried mesa. These indium rich inclusions are sources of defects which propagate through the burying layers. Significant improvement in wipe-off is achieved by etching the indium charges prior to use and by utilizing a multiple melt-back process before the epitaxial growth of burying layers.

Preservation of InP substrates in vapor phase epitaxy: The effect of excess PH3

During vapor phase epitaxy, PH3 is generally used to preserve InP substrates. While PH3 is effective in reducing thermal decomposition, we find that excessive PH3 can produce morphological imperfections on the substrate surface. It is shown that in the temperature range of 675 to 700°C there is an optimum PH3 pressure under which the InP substrate surface morphology remains unchanged.

Effect of p‐n junction position on the performance of InGaAsP light emitting diodes

The power‐speed relationship of 1.3‐μm InGaAsP light emitting diodes is examined as a function of the p‐n junction position within the active layer. It is shown that a gradual displacement of the p‐n junction into the InGaAsP layer results in devices with increased speed and lower output power. To account for the experimental findings junction displacement is modeled in terms of both electron and hole injection.