Sergio Pellegrino

Production of semi‐insulating layers in n‐doped InP by Fe implantation

A detailed study of Fe implantation and damage annealing in indium phosphide is presented. The technological goal was to obtain thermally stable semi‐insulating layers in n‐type InP. Different characterization techniques were employed, including structural (x‐ray diffraction, Rutherford backscattering spectrometry, and transmission electron microscopy), chemical (secondary ions mass spectrometry), and electrical (current‐voltage) measurements. Both undoped and n‐type (Sn) doped substrates were implanted with Fe doses ranging from 5×1011 to 2.2×1014 cm−2 and annealed at a temperature of 650 °C. The high doses used to compensate n+ doping caused amorphization of the material. The reordering process of the amorphous layers and its influence on the Fe redistribution properties were studied in detail. The activation of the implanted Fe atoms after annealing was derived. Although the recovery process of the amorphized layer appears to be rather complex, our results show that good crystal quality and full compen...

Ion implantation and annealing of Fe for semi-insulating layers formation in InP

Abstract We investigated the Fe ion implantation and annealing processes used to obtain semi-insulating buried layers in InP epitaxial structures for current confinement in laser device application. SIMS and RBS-channeling were used as analytical tools. The results show that the annealing is a rather complicated process when their plant causes sample amorphization: high surface reactivity, anomalous dopant diffusion and segregation at damage sites together with inhomogeneous lattice reconstruction are observed.

Quantum-well-laser mirror degradation investigated by microprobe optical spectroscopy

A study of facet degradation of InGaAs quantum well lasers is reported. We tune up a Raman and photoluminescence micro-probe technique for determining the crystal structure and the temperature profile of the cladding layer, in steps of approximately 1 micrometer, with a temperature resolution better than 1 degree Kelvin. The cladding layer composition and cross- section temperature profile have been monitored during operation. A clear correlation between the facet degradation and the type of protective coating is found.

Design of Al-free and Al-based InGaAs/GaAs strained quantum well 980-nm pump lasers including thermal behavior effects on E/O characteristics

A 2D thermal simulator and a model to evaluate high power lasers characteristics have been developed. With these models it was possible to optimize cavity length of InGaAs/GaAs (Multiple) Quantum Well 980 nm lasers realized both with Al-based and Al-free confining layers. A comprehensive experimental investigation of the influence of cavity length and temperature on the laser emission wavelength has been performed. This allows a fine trimming of the devices to match the Erbium doped fiber absorption bandwidth.

Design of high power ridge waveguide 980 nm pump lasers

The design of ridge waveguide semiconductor pump lasers poses particular simulation problems, since an accurate modeling of the electric and thermal effects and of the optical guiding capabilities is needed. We developed a model whose self-consistent application allows the evaluation of, among others, the threshold current of the lasing mode and the gain margin of the higher order modes, the P-I characteristic, the power coupled in the fiber, and the far field pattern. Particular attention is paid to the experimental verification of the transverse single mode operation region, and its evolution at high injection levels. The appropriate conditions for operation in the 150 - 200 mW single mode output power range have been found.

Disordering of InGaAs/GaAs strained quantum well structures induced by rare gas ion implantation

In this work we have investigated the effect of various implantation schemes on In(0.2)GaAs/GaAs/AlGaAs Single Quantum Well, where the implanted species are Argon and Helium, with doses in the range 1E12 to 1E14 at cm^2, at energy spanning 270 - 400 KeV and 30 to 50 KeV for Ar and He, respectively. Repetitive annealing processes were carried out between 735 and 870 degree(s)C and the interdiffusion was deduced by photoluminescence measurements. A maximum of 20 nm shift from He ion implanted Quantum Well with an high degree of reconstruction has been recorded, thus allowing the application of this disordering scheme for the realization of optoelectronic devices.