Application of step-scan FTIR to the research of quantum cascade lasers

The principle of step-scan Fourier transform infrared （FTIR） spectroscopy is introduced. Double modulation step-scan FTIR technique is used to obtain the quantum cascade laser＇s stacked emission spectra in the time domain. Optical property and thermal accumulation of devices due to large drive current are analyzed.

High-Power and High-Efficiency 650nm-Band AlGaInP Visible Laser Diodes Fabricated by Ion Beam Etching

High power and high-slope efficiency 650nm band real-refractive-index ridge waveguide AlGaInP laser diodes with compressive strained MQW active layer are formed by pure Ar ion beam etching process.Symmetric laser mesas with high perpendicularity,which are impossible to obtain by traditional wet etching method due to the use of a 15°-misoriented substrate,are obtained by this dry etching method.Laser diodes with 4μm wide,600μm long and 10%/90% coat are fabricated.The typical threshold current of these devices is 46mA at room temperature,and a stable fundamental-mode operation over 40mW is obtained.Very high slope efficiency of 1.4W/A at 10mW and 1.1W/A at 40mW are realized.

SOI Waveguides Fabricated by Wet-Etching Method

SOI waveguides fabricated by wet-etching method are demonstrated. The single mode waveguide and 1×2 3dB BBI splitter are analyzed and designed by three dimensional beam propagation method to correct the error of effective index method and guided mode method. The devices are fabricated. Excellent performances, such as low propagation loss of -1.37dB/cm, low excess of -2.2dB, and good uniformity of 0.3dB, are achieved.

Etching Behavior of GaN/GaAs(001) Epilayers Grown by MOVPE

Wet etching characteristics of cubic GAN (c-GaN) thin films grown on GaAs(001) by metalorganic vapor phase epitaxy (MOVPE) are investigated. The samples are etched in HCl, H_3PO_4, KOH aqueous solutions, and molten KOH at temperatures in the range of 90～300 ℃. It is found that different solution produces different etch figure on the surfaces of a sample. KOH-based solutions produce rectangular pits rather than square pits. The etch pits elongate in [1(1-bar)0] direction, indicating asymmetric etching behavior in the two orthogonal <110> directions. An explanation based on relative reactivity of the various crystallographic planes is employed to interpret qualitatively the asymmetric etching behavior. In addition, it is found that KOH aqueous solution would be more suitable than molten KOH and the two acids for the evaluation of stacking faults in c-GaN epilayers.

Application of Wet Chemical Etching in Fabrication Process of GaAs/AlGaAs Quantum Dot Arrays

于2010-11-23批量导入

Photoluminescence characteristics of GaAs/AlGaAs quantum dot arrays fabricated by dry and dry-wet etching

GaAs/AlGaAs quantum dot arrays with different dot sizes made by different fabrication processes were studied in this work. In comparison with the reference quantum well, photoluminescence (PL) spectra from the samples at low temperature have demonstrated that PL peak positions shift to higher energy side due to quantization confinement effects and the blue-shift increases with decreasing dot size, PL linewidths are broadened and intensities are much reduced. It is also found that wet chemical etching after reactive ion etching can improve optical properties of the quantum dot arrays.

The design of cascaded resistors in a new analog switch two-step ADC architecture

In this paper we introduce a new Half-flash analog switch ADC architecture. And we discuss two methods to design the values of the cascaded resistors which generate the reference voltages. Derailed analysis about the effect of analog switches and comparators on reference voltages, and the methods to set the resistor values and correspond;ng voltage errors are given.

UV-photooxidation as pretreatment step in inorganic analysis of environmental samples

Many laboratories deal with the determination of heavy metals, carbon, nitrogen and phosphorus. The first step in chemical analysis is a proper preparation of the investigated samples. The presence of organic substances can cause problems in many analytical methods. This paper describes the application of UV irradiation as a method of destruction of organic matter in the investigated samples.