摘要:

An important problem in processing the infrared detector material Hg1−xCdxTe is avoiding undue mercury loss. Here we quantify that loss and apply the information to the annealing of ion implanted Hg1−xCdxTe. We thus extend the work of Takitaetal. on Hg loss in HgTe to the ternary Hg1−xCdxTe. The Hg loss is generated with a thermal‐pulse annealing system and measured by Rutherford backscattering spectrometry (RBS). The loss rate is studied as a function of temperature, composition, and surface preparation (chemimechanical and contactless polishing). For each set of conditions the data is fit to an Arrhenius equationN⧠/t=A exp(−ΔE/kT) and the fitting parametersAand ΔEare determined. ΔEranges from 1.0 to 2.5 eV andAvaries from 1023to 1036atoms/cm2 s. Channeling RBS was also used to study the effect of thermal pulse annealing on boron implanted material. The rate of change of the minimum yield (χmin) with depth, which can be related to certain types of damage, was consistent with the calculated implant damage profile. A 260 °C 8 s anneal restored the crystal quality to better than the as‐received material, as observed by channeling.

ISSN:0734-2101    

DOI:10.1116/1.572251

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

A comparison of low temperature electron beam induced current imaging in the scanning electron microscope and surface defect etch studies has identified subgrain boundaries and isolated dislocations as electrically active recombination centers inp‐type solid state recrystallized (Hg1−X,CdX)Te withX=0.3. The ‘‘spotty’’ appearance of these images is attributed to enhanced recombination at Te‐rich precipitates decorating dislocations in the subgrain boundaries.

ISSN:0734-2101    

DOI:10.1116/1.572252

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

Improvements to a photoneutralization technique for accurately determining compensation densities in narrow‐gap Hg1−xCdxTe are discussed. A more comprehensive theoretical understanding of the electron mobility as a function of optically excited carrier density has been established, incorporating a theory for dynamic dielectric screening in the treatment of electron‐hole scattering. In addition, uniform carrier generation has been demonstrated using two‐photon absorption of CO2laser radiation for compositions in the range 0.24

ISSN:0734-2101    

DOI:10.1116/1.572253

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

Recently developed bonding theory, applied to HgTe and CdTe, predicts the elastic and plastic rigidity of the two compounds relative to each other and relative to silicon.

ISSN:0734-2101    

DOI:10.1116/1.572254

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

Physical reasons are presented for the coherent potential approximation (CPA) calculation method’s abillity to predict little band gap bowing or alloy scattering, while at the same time predicting large deviation from virtual crystal behavior in other energy ranges. Accurate treatment of structural properties requires that calculations be doubly self‐consistent: a density functional method plus CPA is needed. Experimental values of bond energies are greater than those predicted by simple theories. Weakened HgTe bonds in alloys help to explain the loss of Hg when the materials undergo surface treatments.

ISSN:0734-2101    

DOI:10.1116/1.572255

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

This paper presents the first theoretical treatment of the electronic structure of Hg1−xMnxTe. As in the authors’ previous work on Hg1−xCdxTe, a semiempirical tight binding approach is employed, based in part on atomic energy levels, Harrison’s universal tight binding scheme, and existing experimental band structure information. The occupied Mn spin‐polarizeddbands are discussed and shown to have little effect on the states near the band edges. Thes–pelectron ‘‘complex band structure’’ of Hg1−xMnxTe is calculated in the CPA. Previous results for Hg1−xCdxTe are extended and used as a basis of comparison. The more rapid increase of the band gap withxin Hg1−xMnxTe is shown to result from the larger energy difference between cationslevels. This difference also gives rise to more pronounced disorder effects in Hg1−xMnxTe. These are discussed in the context of the CPA results for damping, band gap bowing, and the limiting electron mobilities.

ISSN:0734-2101    

DOI:10.1116/1.572256

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

HgCdTe heterojunctions consisting of a wide band gapn‐type Hg1−xCdxTe layer grown epitaxially on a narrow band gap  p‐type Hg1−yCdyTe substrate (x>y) were studied. The heterojunction transition region betweenxandymaterials was found to be graded over distances of about 0.4 to 0.8  μm. The position of the  p–njunction depletion layer within the graded transition region was the major factor controlling the heterojunction properties. When the depletion layer was located near the narrow band gap material, normal photodiode behavior was observed. When the depletion layer was at the center of the transition region or near the wide band gap material, a potential barrier was formed which inhibited minority carrier photocurrent originating in the  p‐type material from crossing the heterojunction. Qualitative energy band models based on the analysis of HgCdTe heterojunctions recently published by Migliorato and White were constructed to explain the observed results.

ISSN:0734-2101    

DOI:10.1116/1.572258

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

The energy band offsets play a critical role in the electrical properties of heterojunctions. We raise here serious questions regarding the precision and accuracy of the measured and calculated energy band offsets in HgCdTe heterostructures. We argue that the Anderson model prescription for the offsets is not useful and is not correct for abrupt heterojunctions when narrow band gap semiconductors are the constituents of the heterostructure. New values for the photoionization energy of Hg1−xCdxTe are given and the reliability of these values for determining the offset is discussed.

ISSN:0734-2101    

DOI:10.1116/1.572259

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

A method is described for the separation of bulk and surface recombination parameters using experimentally measured photoconductive decay curves. Curve fitting procedures using numerical solutions to the time dependent hole continuity equation permit a unique determination of surface recombination velocities and bulk lifetime. The method is applied to thick and thin films of HgCdTe to determine recombination velocities at several technologically important interfaces. Values of recombination velocity ranged from 300 to 20 000 cm/s depending upon material growth method and surface preparation. Experimentally observed deviations from the assumed model are discussed in terms of a spatially dependent bulk lifetime.

ISSN:0734-2101    

DOI:10.1116/1.572260

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

The optically modulated absorption (OMA) effect has been examined inp‐type (NA−ND≊2×1015cm−3) Hg0.785Cd0.215Te. The effect has been used to measure the excess hole lifetime for temperatures between 85 and 250 K. The measured lifetimes agree with the results of photoconductivity (PC) decay measurements performed on the same samples. The measured lifetimes also indicate that an Auger process is the dominant recombination mechanism at temperatures above about 150 K, while a Shockley–Read–Hall process controls the lifetime below this temperature. In addition, it was found that the OMA signal exhibits extremely large phase‐interference effects when coherent radiation is used for the probe beam. These effects have been both experimentally and theoretically investigated.

ISSN:0734-2101    

DOI:10.1116/1.572261

出版商:American Vacuum Society    

年代:1983

数据来源: AIP