ELECTRON-CYCLOTRON-RESONANCE PLASMA-ETCHING OF HGTE-CDTE SUPERLATTICES GROWN BY PHOTO-ASSISTED MOLECULAR-BEAM EPITAXY

In order to form HgTe-CdTe superlattice diode arrays, a well-controlle d etch process must be developed to form mesa structures on HgTe-CdTe superlattice layers. Wet etch processes result in nonuniform, isotropi c etch profiles, making it difficult to control etch depth and diode s ize. In addition, surface films such as a Te-rich layer may result aft er wet etching, degrading diode performance. Recently, a dry etch proc ess for HgTe-CdTe superlattice materials has been developed at Martin Marietta using an electron cyclotron resonance plasma reactor to form mesa diode structures. This process results in uniform, anisotropic et ch characteristics, and therefore may be a better choice for etching s uperlattice materials than standard wet etch processes. In this paper, we will present a comparison of etch processes for HgTe-CdTe superlat tice materials using electron microscopy, scanning tunneling microscop y, surface profilometry and infrared photoluminescence spectroscopy to characterize both wet and dry etch processes.