Showing papers by "Barry Miller published in 1982"
TL;DR: In this paper, the Fermi level difference of p-InP and H/sup +//H/sub 2/ (0.9 +/- 0.2 eV) was shown to be a function of metal work functions.
Abstract: Noble metal incorporation in the surface of p-type semiconductor photocathodes to catalyze hydrogen evolution leads to efficient solar to chemical conversion if a set of energetic and kinetic criteria are satisfied: (1) the semiconductor-catalyst junction barrier height must be equal to or greater than that of the semiconductor H/sup +//H/sub 2/ junction; (2) the recombination velocity of photogenerated electrons at the semiconductor-catalyst interface must be low; (3) the overpotential for hydrogen evolution at solar cell current densities (approx.30 mA/cm/sup 2/) must be minor. Because of substantial differences in the vacuum work functions of Pt, Rh, Ru, and the (redox potential of the) H/sup +//H/sub 2/ couple, the barrier heights for junctions of each of the four systems with p-InP ought to vary widely. Yet experiments show that all p-InP(M)/H/sup +//H/sub 2/ junctions, where M = Pt, Rh, Ru, or no metal, have essentially the same approx.0.7-V gain in onset potential for hydrogen evolution relative to Pt/H/sup +//H/sub 2/. We attribute the similarity to the known lowering of metal work functions upon hydrogen alloying. Such alloying increases the barrier height and thereby the gain in onset potential over that anticipated from the vacuum work functions. The barrier height, measured as themore » limiting value of onset potential gain at high irradiance, approaches in all cases the Fermi level difference of p-InP and H/sup +//H/sub 2/ (0.9 +/- 0.2 eV). That Fermi level pinning by interfacial states is not the cause of the similar barriers is evident from the reversible decrease in onset potential with hydrogen depletion and by a unity diode perfection factor of the p-InP(Rh)/H/sup +//H/sub 2/ photocathode, which indicates no measurable interfacial recombination of photogenerated carriers. In agreement, the quantum efficiency of carrier collection (hydrogen evolution) nears unity.« less
184 citations
TL;DR: In this paper, wet and dry etching techniques for GaInAsP/InP laser structures allow the reproducible fabrication of planar and vertical walled facets and grooves.
Abstract: Recent advances in wet and dry etching techniques for GaInAsP/InP laser structures allow the reproducible fabrication of planar and vertical walled facets and grooves These elements provide efficient mirrors and interstage couplers that may provide the basis for a new generation of monolithic integrated optical devices Initial experimental results on etched facet lasers and groove-coupled two-section lasers verify theoretical expectations
97 citations
TL;DR: In this paper, the formation of hydrated indium oxide on the (111)A (indium) face of p-InP when the crystal is etched in either air-saturated acid or methanol-bromine, or when used as photocathode in the p-semiconductor liquid junction solar cell.
Abstract: Spectroscopic ellipsometry and low-energy (helium) ion scattering spectroscopy show the formation of hydrated indium oxide on the (111)A (indium) face of p-InP when the crystal is etched in either air-saturated acid or methanol-bromine, or when used as photocathode in the p-semiconductor liquid junction solar cell. The stability and efficiency of the cell depend on the presence of a thin, large band gap layer of indium oxide. The relatively better performance of p-InP over p-GaAs in such a cell is attributed to the different oxide surface chemistry of the latter, which leads to contamination by elemental arsenic. The favorable performance of p-InP in the V(II)-V(III)-HCl cell is ascribed to the reduction of recombination sites in the forbidden gap by termination of the lattice by the oxide.
51 citations
TL;DR: In this article, the spectral properties of two-section GaInAsP/InP laser systems were studied and single-longitudinal mode light pulses of less than 750 ps length were produced by driving the long section of the laser only or by prebiasing the long cavity and modulating the short section with a current pulse of 1 ns halfwidth.
Abstract: The spectral behaviour of monolithic two-section GaInAsP/InP lasers is studied. Single-longitudinal-mode light pulses of less than 750 ps length are produced by driving the long section of the laser only or by prebiasing the long cavity and modulating the short section with a current pulse of 1 ns halfwidth. The wavelength of the output light can be changed by varying the operation temperature or the prebias level.
45 citations
20 citations
TL;DR: In this article, an efficient and simple optical interconnection between active semiconductor components by deposition and spin coating is proposed, which shows a low-threshold (2.0 kA/cm2) and high-coupling (81%) operation of a laser-polyimide/SiO2 slab waveguide integrated on a GaInAsP/InP chip.
Abstract: We propose an efficient and simple optical interconnection between active semiconductor components by deposition and spin coating. The demonstration shows a low-threshold (2.0 kA/cm2) and high-coupling (81%) operation of a laser-polyimide/SiO2 slab waveguide integrated on a GaInAsP/InP chip.
20 citations
TL;DR: In this paper, planar (011) mirror facets have been exposed on GaInAsP/InP double heterostructures for the first time using an initial RIE that cuts through the stop-etching plane.
Abstract: Using angled reactive ion etching (RIE) and wet chemical etching (WCE), planar (011) facets have been exposed on (100) GaInAsP/InP double heterostructures for the first time. Positively sloped wall profiles observed previously for this orientation are eliminated by an initial RIE that cuts through the stop-etching (111)A plane. These (011) mirror facets are preferred over (011) for most state-of-the-art low-threshold lasers.
13 citations
TL;DR: In this article, an efficient and simple optical interconnection between active semiconductor components by deposition and spin coating is proposed, which demonstrates low-threshold (2.0 kA/cm2) laser operation and a low-loss waveguide interconnection on a GaInAsP/InP chip.
Abstract: We propose an efficient and simple optical interconnection between active semiconductor components by deposition and spin coating. Details of the waveguide design, the fabrication technique, and a promising material combination are given. Experimental results with an integrated laser-polyimide/SiO x ( x \sim 2 ) waveguide combination demonstrate low-threshold (2.0 kA/cm2) laser operation and a low-loss waveguide interconnection (81 percent coupling efficiency) on a GaInAsP/InP chip.
12 citations
TL;DR: In this article, a liquid phase epitaxial grown Cd-doped InGaAsP/InP double-heterostructure stripe laser was found to yield very high external differential quantum efficiency, ηext ∼74% in relatively long cavity lasers compared to that of Zn−doped ones.
Abstract: Liquid phase epitaxial grown Cd‐doped InGaAsP/InP double‐heterostructure stripe lasers were found to yield very high external differential quantum efficiency, ηext ∼74% in relatively long cavity lasers compared to that of our Zn‐doped ones. Since Cd was found to diffuse only slightly into the active layer, the high ηext as well as the lower threshold current in the Cd‐doped lasers are attributed to lower concentration of nonradiative recombination centers. The broad area lasers have lower ηext than the respective stripe lasers. Moreover, ηext is insensitive to the heat sink temperature in the range 20–70 °C in the stripe lasers while it drops considerably in the broad area ones.
2 citations