SIMS depth profiling of InGaAsN/InAlAs quantum wells on InP

Quaternary InxGa1-xAsyN1-y (x > 0.53, 1 - y <0.03) QWs grown between In0.52Al0.48As barriers on InP substrate were analyzed by SIMS depth profiling. For the determination of the indium and nitrogen calibration curves, InxGa1-xAs (0 <= x <= 1) standards were used which were partly implanted with nitrogen at an energy of 75 keV and a dose of 5 x 1015 N2 molecules/cm2. The QW structures were grown by molecular beam epitaxy with a nitrogen plasma source. MCs+ secondary ions (M=Al, Ga, In, As and N) were used for depth profiling. Nitrogen is found incorporated in InxGa1-xAs layers in concentrations needed for the intended laser applications. The nitrogen concentration can be reliably assessed by SIMS. Thickness and compositional data agree with the nominal data and the data determined by high resolution X-ray diffraction. The In-content is apparently not influenced by the incorporation of nitrogen and vice versa

High In-content InP-substrate based GaInAsN and GaInAsN QW diode lasers emitting in the 2.2 to 2.3 µm wavelength range

We report on the growth and characterization of high In-content quaternary Ga(1-x)In(x)As(1-y)N(y) (0.78 lt = x lt = 1,y lt = 0.02), grown by plasma assisted molecular beam epitaxy on InP-substrates. First, the incorporation of nitrogen in high In-content GaInAsN was analyzed by Raman spectroscopy, revealing that already a small amount of Ga in the GaInAsN alloy (x>=0.92) leads to an almost complete change from pure In-N bonding to nitrogen atoms bonded to at least on Ga-neighbor. Next, strained Ga(0.22)In(0.78)As(0.99)N(0.01)/Al(0.48)In(0.52)As QWs were optimized for long-wavelength emission. In this way room-temperature photoluminescence could be achieved at a wavelength of 2.3 µm for 11 nm wide QWs. Finally, Ga(0.22)ln(0.78)As(0.99)N(0.01) QW-diode lasers were realized, employing lattice matched Al(0.15)Ga(0.32)In(0.53)As as the material for the barriers as well as for the separate confinement layers. InP was used for the cladding layers. Ridge waveguide lasers were fabricated without any post-growth thermal annealing. These devices showed pulsed lasing up to a heat sink temperature of 190 K, for which lasing was at 2.23 µm. Higher operating temperatures as well as cw-operation were inhibited by the high threshold current density of almost 2 kA/cm2 at 190 K, but room-temperature electroluminescence could be observed at wavelengths up to 2.4 µm. As annealing studies on GaInAsN QW-test structures indicate, post-growth annealing of the laser material will lead to a significant improvement in laser performance

2 µm room-temperature diode lasers for Co(2)-detection

We report on the detection of CO2 using diode lasers grown by low-pressure MOCVD on InP-substrate. Employing the InP substrate based GaInAsP material system and technology, well developed and established for fabrication of 1.3 mu m and 1.55 mu u semiconductor lasers for optical fiber communication, the long wavelength limit of this material system is explored. In order to match the CO2 absorption line around 2 mu m - detection limit at 2.004 mu m: 6.1 mu g/m3 (approx. 5 ppb) - the active region of the laser consists of compressively strained GaInAs quantum wells (QWs) and tensile strained GaInAs barriers. The CO2 absorption at 2 mu m can be covered by these devices which are manufactured using standard process technology and operate at room temperature. Increasing the heat sink temperature up to 310 K the emission wavelength of these devices can be tuned up to 2.04 mu m. Replacing the ternary barriers by quaternary GaInAsP the emission wavelength extends up to 2.09 mu m at a heat sink temperature of 330 K. In a first demonstration laser diodes with ternary barriers were applied to tunable diode laser absorption spectroscopy (TDLAS) of CO2 25 per cent CO2 in N2 was measured operating the devices at 287 K