Roland Gessner

1.55 mu m gain-coupled quantum-well distributed feedback lasers with high single-mode yield and narrow linewidth

The fabrication and characteristics of gain-coupled 1.55- mu m GaInAlAs quantum-well metal-clad ridge-waveguide distributed-feedback lasers are discussed. The gain-coupling mechanism was provided by a thin ternary loss grating layer with an estimated gain-coupling strength of about 30/cm. For as-cleaved devices, the single-mode yield was as high as 70 and 95% for 600- and 800- mu m-long devices, respectively. Typical threshold currents were 40 and 55 mA, respectively. Both the high single-mode yield and the pronounced asymmetric spectra were calculated theoretically and give a strong indication that a significant amount of gain coupling was realized in the laser structure. For a 600- mu m-long device, a continuous-wave (CW) output power of 10 mW and a minimum linewidth of 1.6 MHz were measured.<<ETX>>

1.57 mu m strained-layer quantum-well GaInAlAs ridge-waveguide laser diodes with high temperature (130 degrees C) and ultrahigh-speed (17 GHz) performance

The fabrication of GaInAlAs strained-layer (SL) multiple-quantum-well (MQW) ridge-waveguide (RW) laser diodes emitting at 1.57 mu m is discussed. Due to an optimized layer structure, a very high characteristic temperature of 90 K was obtained. As a consequence for episide-up mounted devices, the maximum continuous wave (CW)-operation temperature is 130 degrees C. At room temperature, a maximum output power of 47 mW was measured for 600- mu m-long lasers with one high-reflection coated facet. The low series resistance of 4 Omega (2 Omega ) for 200- mu m-(400- mu m)-long devices yields an ultrahigh 3-dB bandwidth of 17 GHz. These static and dynamic properties also result from a high internal quantum-efficiency of 0.83 and a high differential gain of 5.5*10/sup -15/ cm/sup 2/.<<ETX>>

SELECTIVE ETCHING AND EPITAXIAL REFILLING OF SILICON WELLS IN THE SYSTEM SiH4/HCl/H2

Wells were etched in (100) silicon by different kinds of selective etching and were selectively refilled by using different gas systems. Masking materials were SiO2 and Si3N4; for the refilling the systems SiCl4/H2 and SiH4/HCl/H2 were studied. By using a combination of weak anisotropic gas etching with HCl (Si3N4 films as mask) and of SiH4/HCl/H2 as refilling system, plane surfaces without ridges at the boundary of the mask and without nuclei on the mask were reached. The results were obtained by SEM, light microscopic and profile investigations and are compared with the other kinds of etching and refilling.

Very low threshold current density (Al)GaInAs/Al(Ga)InAs laser structures grown by atmospheric pressure MOVPE

The growth of (Al)GaInAs/Al(Ga)InAs structures of high quality for laser devices using metalorganic vapor-phase epitaxy (MOVPE) at atmospheric pressure is described. SeH/sub 2/ and DEZn have been used as the dopant precursors. Se is an appropriate dopant for the n-type confinement layers of lasers, showing a distinctly higher electrical activation in AlInAs than Si. Zn is superior to Mg as a dopant for the p-type confinement layers of lasers as its apparent diffusion coefficient is about one order of magnitude lower than that of Mg in AlInAs. Broad-area double-heterostructure (DH) lasers (device length=800 mu m) operating at 1.66 mu m and 1.55 mu m are shown to have I/sub th/ values as low as 2.3 kA cm/sup 2/ and 1.5 kA/cm/sup 2/, respectively. With broad-area separate-confinement-heterostructure multiple-quantum-well (SCH-MQW) lasers (device length=800 mu m) emitting at 1.524 mu m, threshold current densities as low is 0.92 kA/cm/sup 2/ can be achieved.<<ETX>>