High quality GaAs-based resonant tunneling diodes for high frequency device applications

The influence of the barrier thickness (L/sub B/) and the spacer length (L/sub S/) on the current/voltage behavior of AlAs/GaAs/AlAs resonant tunneling diodes (RTDs) to achieve a high peak current density (J/sub p/) and a low valley current density (J/sub V/) for device applications at room temperature was studied. The samples were grown by molecular beam epitaxy. With increasing L/sub B/ in the range between 3 monolayers (ML) and 6 ML a drastic increase of the peak-to-valley current ratio (J/sub P//J/sub V/) up to a maximum value of 5 (12) at 300 K (77 K) for L/sub B/=6 ML is observed. Simultaneously, J/sub p/ decreases exponentially with thicker barriers. A maximum available current density in the negative-differential-resistance region of Delta J=J/sub p/-J/sub V/=165 kA/cm/sup 2/ at 300 K is achieved for 4 ML thick AlAs barriers. No influence of the emitter spacer length variation on J/sub p/ for L/sub S/>10 nm was found. However, for l/sub S/<10 nm J/sub p/ increases with decreasing L/sub S/ (maximum improvement of 60% for L/sub S/=0.5 nm). The PVR can be significantly improved by using a pseudomorphic InGaAs prewell layer for carrier injection.<
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