Scanning tunneling microscopy of etched HgTe/CdTe superlattices

Abstract

Scanning tunneling microscopy is demonstrated for determining the surface morphology of etched Hg-based semiconductors. Wet etching of HgTe/CdTe superlattices used a Br-based etch solution while dry etching used methyl-free radicals formed by electron cyclotron resonance in a reactive ion etching reactor. Both techniques produced smooth surfaces with random features over large regions. Features ranged in height from 1 to 5 nm for wet etching, while the smoothest dry etched sample had random features with an average height of 40 nm. Near mesa structures, evidence of differential etching was observed between the different composition layers in the HgTe/CdTe superlattices for both wet and dry etched samples.

The use of atomic hydrogen for low temperature oxide removal from HgCdTe

“…[23][24][25][26][27][28][29] It is believed that similar oxides are present on HgCdTe. [23][24][25][26][27][28][29] It is believed that similar oxides are present on HgCdTe.…”

Characterization of the CH4/H2/Ar high density plasma etching process for HgCdTe

“…Recent works by Keller et al 8,9 have begun to address the polymer deposition issue through the addition of nitrogen to the plasma. Surface roughness and its reduction has also been addressed in recent works, 12,13,15 as has the issue of surface stoichiometry, 12,14 identified as preferential Hg and Te loss. There has been little work on characterization of the changes in electrical properties of HgCdTe subjected to the etching process.…”

“…[7][8][9][10][11][12][13][14][15][16][17][18] High density plasmas have a number of Characterization of the CH 4 /H 2 /Ar High Density Plasma Etching Process for HgCdTe advantages over the conventional parallel plate radio frequency (rf) plasma used for etching semiconductors. High density plasmas have high fluxes of low and controllable ion energies (20 eV and up) that permit high etch rates while providing the capability for low damage etching.…”

The use of atomic hydrogen for substrate cleaning for subsequent growth of II-VI semiconductors

“…While we did not have the in-situ analytical capabilities to check this assertion, we could perform ex-situ reflectance measurements to look for gross shifts in stoichiometry. 35 Measurements of the E1 reflectance peaks probes a layer approximately 100 nm thick. Measurements of the E 1 reflectance peak before and after atomic hydrogen cleaning were identical within instrumental resolution.…”