Jaeseok Lee

Specific resistivity of ohmic contacts to n‐type direct band‐gap III‐V compound semiconductors

Contact resistivity curves are given in terms of intrinsic barrier height and doping level for ohmic contacts to n‐type direct band‐gap III‐V semiconductor compounds, including AlxGa1−xAs. The results are based on a rigorous treatment of carrier transport across the metal‐semiconductor interface. They show that the resistivity behaves quite differently from what might be expected from the usual notion of the effects of doping and barrier height on the resistivity. As such, the results can be used as a useful guide in attempts to lower the contact resistivity.

Microlens Array Fabrication by Chemical Mechanical Polishing

Chemical mechanical polishing (CMP) was used to shape hexagonally arranged 20 μm diam cone-shaped structures, prepared by wet etching of Coming 2496 glass, into microlenses. Edge rounding, which occurs during CMP due to a higher removal rate at the edges, was utilized for shaping of the microlenses. Microlenses with an H/D ratio of ∼ 1/10 and radius of curvature of 27.5 μm were obtained. CMP variables that affect the contact pressure and material removal rate are downpressure, linear velocity, slurry, and properties of the pad. These variables being external to substrate provide great flexibility and, hence, suitability of the process for a wide range of materials.