Experimental realization of the bound state resonant tunneling transistor

Summary form only given. Bound states resonant tunneling transistors (BSRTTs) with direct contacts to ultrathin base layers (~60 Å) have been experimentally realized. In the BSRTT structure, bound states are created in the quantum well by using a base material with a low band gap. Electrons in these bound states form a low-resistance base region for application of bias to the device. Resonant tunneling of electrons via the second energy level in the well results in negative differential transconductance (NDT) or negative differential resistance (NDR) in the output current. This NDT or NDR can be used for applications in high-speed digital circuits to reduce the complexity of conventional transistor technology. The BSRTTs studied consist of a 3000-Å In_0.53Ga_0.47As emitter layer doped at 5×10¹⁸ cm^-3, an emitter stepped barrier which includes a 500-Å n⁺ and a 300-Å undoped In_0.52Al_0.48 layer, a 20-Å AlAs barrier, a 60-Å In_0.75Ga_0.25As base layer doped at 5×10¹⁸ cm^-3, a 20-Å AlAs barrier, a 1000-Å undoped In_0.52Al_0.48As collector barrier, and a 5000-Å In₀₅₃GA₀.₄₇As collector layer doped at 5×10¹⁸ cm^-3. Device testing results are reported