The sequential tunneling behavior in InP/InGaAs superlattice-emitter bipolar transistors is demonstrated by theoretical analysis and experimental results. The tunneling mechanism in the InP/InGaAs superlattice structures is analyzed by theoretical calculation. Due to the weak coupled tunneling mechanism, the interesting multiple negative-differential-resistances (NDRs) resulting from the creation and extension of high-field domain in the superlattice are observed at room temperature. Experimentally, the transistor performances, including a high current gain of 454, a low collector-emitter offset voltage of 80 mV, and a pronounced multiple NDRs, are achieved. The proposed structures may provide good potential for signal amplifiers and multiple-valued logic circuit applications. (c) 2006 Elsevier B.V. All rights reserved.