Hu Xierong

Depth profiles of fluorine in 19F+ ion-implanted Pb1−xSnxTe and CdTe

The 19F(p,αγ)16O resonance nuclear reaction at 872.1 keV, with Γ = 4.2 keV was used to measure the depth profiles of fluorine in 19F+-implanted Pb1−xSnxTe and CdTe samples. A deconvolution procedure was performed to extract the depth profiles from the experimental excitation yield curves. The range parameters. Rp, ΔRp and SK, obtained in this experiment were compared with theoretical calculations.

Impact parameter dependence of electronic energy loss for heavy ions at low velocity

Abstract The impact parameter dependence of electronic energy loss for heavy ions colliding at low velocity with atoms has been studied using the shell-wise local electron-density model. Roothaan-Hartree-Fock wave functions are used to calculate the local electron density of the atoms studied. The Brandt-Kitagawa effective stopping power charge theory is modified to incorporate the effective charge obtained using Fermi-level scattering phase shift calculations based on the density-functional formalism. The theoretical results are compared with available experimental measurements.

Nonlinear Fabry-Perot Etalon and Optical Bistability in CdHgTe at 77 K

We report the first observations of nonlinear feature and optical bistability in n-CdHgTe at 77 K and obtained computer simulated curves, then discuss contribution due to thermal effect.

Particular solution for geodesic lenses

On the basis of the analytical method of designing aspherical optical waveguide geodesic lenses [J. Opt. Soc. Am. 69, 1248 (1979)], a particular solution for geodesic lenses without any curvature singularity was obtained.

The Effect Of The Surface Layer Electric Field On The Performance Of Hg0.8 Cd 0.2 Te Photovoltaic Detectors

In recent years ion implantation has been used to develop MCT and other infrared photovoltaic detectors, However, the implanted ions usually have a nonuniform depth profile in the implanted layer, with the typical depth less than lμm, within which the concentration of the implanted species may change over 3 to 4 orders. Thus within the layer there is an electric field outside the space-charge region. The electric field can be estimated with its intensity as high as 1x102-1x103v/am at 77k. In the present work the effect of the electric field is studied to show its way to effect the performance of the infrared photovoltaic detectors. Using the formulae obtained in this work, the RoA, product, responsibility, noise and detectivity of n-on-p Hgo.8Cd0.2Te photovoltaic detector operating at 77k are calculated for 300k backgrond and 27πfield of view. The results show that they are all related to the electric field in the implanted layer. It is interesting that when the electric field direct to the surface of n-region, namely negative field, the RoAlv=0 product contributed by n-region can not be neglected and the responsibility R,. and detectivity Dℓ, decrease. In the case of positive electric field, responsibility RA and the noise Vn both increase while the Dℓ increases slightly. Our calculation suggests that the proper technology process should be taken in manufacturing the MCT n-on-p infrared photovoltaic detector by use of ion implantation to eliminate the negative field in the n-region in order to avoid the harmful effect. The calculation is performed to show how the electric field in the ion implanted layer on Hg0.8Cd0.2Te to effect the performance of Hg0.8Cd0.2,Te photovoltaic detectors. The result shows that a reverse electric field is unfavorable for the performance of the photovoltaic detectors.

Refractive Index and Extinction Coefficient of Hg1-xCdxTe at 77 and 300 K

We measured refractive index and extinction coefficient of n type Hg1-xCdxTe with the null ellipsometric spectrum method over the visible light region at 77 and 300 K, and the dispersion relation at different temperature is discussed. The value of refractive index at 77 K is smaller than that at 300 K, and the changes of the extinction coefficient curve at 77 K is also smaller than that at 300 K.

Computer Simulation of Sputtering and Atomic Redistribution in Hg0.8Cd0.2Te Targets Under Ar+ Ions Bombardment

The sputtering of Hg0.8Cd0.2Te target by low energy Ar+ ions has been simulated using Monte Carlo method. The simulation results show that the concentration of Hg in the surface region of the target after ion bombardment is lower than the one before ion bombardment, but in a deeper region an excess concentration of Hg is produced due to recoil implantation. The excess concentration of Hg there may act as a donor dopant diffusion source for over doping the acceptor levels in the adjacent region and turn the p-type Hg0.8Cd0.2Te into an n-type material.

Observation of Self-Pumped Phase Conjugation for Two Mutually Coherent Input Beams in a KNSBN Crystal

Two coherent or incoherent stable self-pumped phase conjugations have been obtained simultaneously in a Ce-doped (K0.5Na0.5)2y(Sr0.61Ba0.39)1-yNb2O6 (KNSBN) crystal by using two mutually coherent input beams from a He-Ne laser, and energy translation from one beam to another induces self-pumped phase conjugative reflectivity of one beam above 100%.

The Influence Of Dislocation Scattering On N-Type Hg1-xCdxTe Mobility

The electronic mobility is an important parameter to express HgCdTe characters. The performance of photoconductive detectors, photovoltaic detectors and sprite detectors are all concerned with it. In our work, besides ionized impurity scattering, polar-optical scattering, acoustic deformation potential scattering and piezoelectric scattering, we also consider the dislocation scattering and give the result in accord with experiment. It shows that dislocation scattering is one of the important factors to influence HgCdTe electronic mobility. In our work, we also give a kind of amendment formula of ionized density. In addition, we also discuss the relationships between mobility and temperature and dislocation density. The result shows that, in the region 40K and 100K, the influence of dislocation is important and can not be neglected.

The Influence Of Surface Channel On The Crosstalk Of HgCdTe Photovoltaic Arrays

In application, the HgCdTe photovoltaic arrays exist crosstalk. There are many factors to cause it, and the surface channel is one of them. Because there are electric charges on the surface of HgCdTe photovoltaic device, they can form the surface channel between arrays. We calculate the crosstalk caused by diffusion of carrier through the surface channel under applied voltage. Using the LMC crosstalk instrument, we have measured the crosstalk. The calculative values conform to the result of experiment well. It shows that the surface channel is one of the important factors to effect the crosstalk of HgCdTe photovoltaic arrays. The thicker channel of the surface, the greater crosstalk of the arrays. The crosstalk decreases following with increasing of majority concentration.