| Abstract
| - We report the results of a study of electrosynthesized CdS−HgS heterojunctions using scanning tunnelingmicroscopy (STM), photoluminescence spectroscopy (PL), and electrochemistry. CdS thin films were grownby electrochemical atomic-layer epitaxy (EC-ALE) onto Au(111) substrates and were terminated with asingle HgS monolayer using one of two methods. The first method, which involved the chemical exchangeof the terminal Cd layer with Hg2+, produced a disordered, highly polycrystalline film, as evidenced bythe PL spectrum, which was dominated by CdS trap luminescence. The second method, in which the HgSmonolayer was grown by EC-ALE, resulted in the formation of a high-quality heterojunction. PLmeasurements indicate a high degree of electronic coupling between the CdS substrate and theelectrochemically deposited HgS layer in this case. These findings were confirmed by atom-resolved andmicron-scale STM images.
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