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Nonisothermal transport in InGaAsP-based heterostructure integrated thermionic coolers is investigated experimentally. Cooling on the order of a degree over 1 m thick barriers has been observed. This method can be used to enhance thermoelectric properties of semiconductors beyond what can be achieved with the conventional Peltier effect. © 1999 American Institute of Physics. ͓S0003-6951͑99͒02701-1͔Temperature stabilization of optoelectronic components ͑lasers, filters, switches, etc.͒ is of increasing importance in many high-speed and wavelength division multiplexed fiberoptics communication systems. Heat generation and thermal management in very large scale integrated ͑VLSI͒ circuits is becoming one of the barriers to further increase clock speeds and decrease feature sizes. Solid-state coolers integrated with devices are an attractive way to solve some of these problems. This means alternatives to thermoelectric cooling using Bi 2 Te 3 , the current industry standard, must be found. A solution is to use thermionic emission in heterostructures, a technique that can give significant cooling in conventional materials such as AlGaAs, InGaAsP, or SiGe. 1,2 In this letter, we investigate experimentally nonisothermal electron transport in InGaAsP-based heterostructure integrated thermionic ͑HIT͒ coolers.The conventional thermoelectric effect is based on bulk properties of materials. 3 When electrons flow from a material in which they have an average transport energy smaller than the Fermi energy to another material in which their average transport energy is higher, they absorb thermal energy from the lattice and this will cool down the junction between two materials. In an alternative method, thermionic emission current in heterostructures can be used to achieve evaporative cooling by selective emission of hot electrons over a barrier layer from cathode to anode. 1,2,4,5 Since the energy distribution of emitted electrons is almost exclusively on one side of the Fermi energy, upon the current flow, strong carriercarrier and carrier-lattice scatterings tend to restore the quasiequilibrium Fermi distribution in the cathode by absorbing energy from the lattice, and thus, cooling the emitter junction.In order to investigate experimentally thermionic emission cooling in heterostructures, a single InGaAsP ( gap ϭ1.3 m͒ barrier surrounded by n ϩ -InGaAs cathode and anode layers was grown using metal organic chemical vapor deposition ͑MOCVD͒. Cathode and anode layer thicknesses were 0.3 and 0.5 m and they were doped to 3 ϫ10 18 cm Ϫ3 . The barrier layer had an n doping of 2 ϫ10 17 cm Ϫ3 and was 1 m thick. Mesas with an area of 90ϫ180 m 2 were etched down using dry etching techniques. Ni/AuGe/Ni/Au was used for top and bottom contact metallization. Figure 1 displays the measured temperature on the top and on the bottom of the device as well as the substrate temperature far away from the device as a function of current. All temperatures are relative to the value at zero current. The rise in substrate temperature is an indicatio...

Effects of Si doping on normal incidence In As ∕ In 0.15 Ga 0.85 As dots-in-well quantum dot infrared photodetectors J. Appl. Phys. 99, 083105 (2006); 10.1063/1.2189973High-performance 30-period quantum-dot infrared photodetector

This paper overviews the properties and possible applications of long wavelength vertical-cavity semiconductor optical amplifiers (VCSOAs). A VCSOA operating in the 1.3-m wavelength region is presented. The device was fabricated using wafer bonding; it was optically pumped and operated in reflection mode. The reflectivity of the VCSOA top mirror was varied in the characterization of the device. Results are presented for 13 and 12 top mirror periods. By reducing the top mirror reflectivity, the amplifier gain, optical bandwidth, and saturation output power were simultaneously improved. For the case of 12 top mirror periods, we demonstrate 13-dB fiber-to-fiber gain, 0.6 nm (100 GHz) optical bandwidth, a saturation output power of 3 5 dBm and a noise figure of 8.3 dB. The switching properties of the VCSOA are also briefly investigated. By modulating the pump laser, we have obtained a 46-dB extinction ratio in the output power, with the maximum output power corresponding to 7-dB fiber-to-fiber gain. All results are for continuous wave operation at room temperature.