Hg0.70Cd0.30Te anodic oxidation

Janousek, Bruce K.; Carscallen, Richard C.

doi:10.1116/1.571674

Cited by 20 publications

(6 citation statements)

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“…The compositions of native, anodic, chemical and photochemical oxides, as well as their generation techniques, have all been the subjects of investigation. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] A variety of sample preparations were also examined. Treatments with Br-based etches [2][3][4][5][6]8,10,11,[14][15][16] acids 3,9,16 and ion bombardment 1,3,15 are but a few of the simpler examples of the techniques used.…”

Section: Introductionmentioning

confidence: 99%

Investigation of HgCdTe surface films and their removal

Varesi

Benson

Jaime-Vasquez

et al. 2006

Journal of Elec Materi

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We have examined the formation and removal of native surface films on Hg 1-x Cd x Te (n-type, x 5 0.2). Samples were etched with a Br-based solution and then characterized by spectroscopic ellipsometry and X-ray photoelectron spectroscopy. A second set of measurements was acquired after these samples were exposed to air. The results confirm the formation of a surface layer consisting primarily of oxide(s) following an etch of the samples. It also appears that elemental Te may be a component of the postetch film. We presently believe that the predominant components of the oxide are TeO 2 and CdO. Following the formation of the native oxide we examined its solubility by immersing the samples in several common liquids. While isopropanol and acetone had little effect, de-ionized water, methanol and ethylene glycol each removed significant portions of the HgCdTe surface oxide. Atomic force microscope images suggest that the removal of the surface film may not be entirely uniform. Additionally, it was shown that storage in de-ionized water, methanol, or isopropanol essentially preserves the postetch surface properties.

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Section: Introductionmentioning

confidence: 99%

Investigation of HgCdTe surface films and their removal

Varesi

Benson

Jaime-Vasquez

et al. 2006

Journal of Elec Materi

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“…case of detectors passivated by CdTe in comparison to those passivated by AO. Improvement in the detector performance by CdTe passivation is on the expected lines as the AO/n-HgCdTe interface had been reported to contain large fixed positive charges, [24][25][26][27][28][29][30] leading to over accumulation of n-HgCdTe surface causing degradation in the detector performance. 31,32 The AO is grown by an electrochemical process and the oxidation reaction is reported to be strong enough to damage the HgCdTe (x ϭ 0.2) surface up to a depth of ϳ200 Å beneath the oxide-HgCdTe interface.…”

Section: Detector Performancementioning

confidence: 99%

A CdTe passivation process for long wavelength infrared HgCdTe photo-detectors

Kumar

Pal

Chaudhury

et al. 2005

J. Electron. Mater.

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Passivant-Hg 1-x Cd x Te interface has been studied for the CdTe and anodic oxide (AO) passivants. The former passivation process yields five times lower surface recombination velocity than the latter process. Temperature dependence of surface recombination velocity of the CdTe/n-HgCdTe and AO/nHgCdTe interface is analyzed. Activation energy of the surface traps for CdTe and AO-passivated wafers are estimated to be in the range of 7-10 meV. These levels are understood to be arising from Hg vacancies at the HgCdTe surface. Fixed charge density for CdTe/n-HgCdTe interface measured by CV technique is 5 ϫ 10 10 cm Ϫ2 , which is comparable to the epitaxially grown CdTe films. An order of magnitude improvement in responsivity and a factor of 4 increase in specific detectivity (D*) is achieved by CdTe passivation over AO passivation. This study has been conducted on photoconductive detectors to qualify the CdTe passivation process, with an ultimate aim to use it for the passivation of p-on-n and n-on-p HgCdTe photodiodes.

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“…During the electrochemical formation of the anodic oxide layer, the MCT substrate material is consumed and sharp interfaces have thus been reported to form [2]. Oxide growth is usually carried out using the well established constant current anodisation method [5,9,10] in 0.1 M KOH in 90% ethylene glycol/10% H 2 O.…”

Section: Introductionmentioning

confidence: 99%

Enhancement of the second harmonic signal from Hg1−xCdxTe (MCT) in the presence of an anodic oxide film

Wark

McErlean

Cruickshank

et al. 2010

Journal of Electroanalytical Chemistry

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a b s t r a c tSecond harmonic generation (SHG) is now widely regarded as a valuable tool for investigating electrode surfaces. Typically, most studies have been limited to substrates which lack bulk symmetry and monitoring events such as sub-monolayer formation and surface reconstruction. Here, the development of a model that can be used to quantitatively describe the enhanced SH signal observed in the presence of an anodic oxide film on a non-centrosymmetric substrate, Hg 1Àx Cd x Te (MCT), is described. The aim is to further expand the utility of SHG for probing different electrode systems. The growth of the high quality oxide films was first followed by in situ ellipsometry. For thin films (<100 nm) grown at a constant current density of 150 lA cm À2 , an effectively uniform oxide layer is found with a refractive index n of $2.15 ± 0.05 and exhibiting no absorption of the incident radiation at 632.8 nm (1.96 eV). In the presence of such an oxide film of 58 nm thickness, the second harmonic (SH) signal intensity measured in reflection is found to be significantly enhanced in both the P IN -P OUT and P IN -S OUT polarisation configurations. To quantify the changes observed, each layer in the model is assigned its own symmetry and optical constants at the fundamental, x and harmonic X (= 2x) frequencies and a defined thickness. Modeling of the SH rotational anisotropy experiments carried out at different angles of incidence indicated that most of this increase could be accounted for by multiple reflections of the fundamental wave x = 1064 nm (1.17 eV) in the composite ambient/oxide/MCT layer, with little contribution from charge accumulation at the buried MCT/oxide interface for this oxide thickness.

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Hg0.70Cd0.30Te anodic oxidation

Cited by 20 publications

References 0 publications

Investigation of HgCdTe surface films and their removal

Investigation of HgCdTe surface films and their removal

A CdTe passivation process for long wavelength infrared HgCdTe photo-detectors

Enhancement of the second harmonic signal from Hg1−xCdxTe (MCT) in the presence of an anodic oxide film

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