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The DC performances of InP/InGaAs single and double heterojunction bipolar transistors (SHBT and DHBT) are compared and studied. The temperature-dependent characteristics of both devices are also presented. Due to the use of a 4000 A InP collector, the studied DHBT exhibits a higher breakdown voltage than the SHBT. The common-emitter breakdown voltages of the studied SHBT and DHBT are higher than 2 and 10 V, respectively. In addition, based on the employment of a tunnelling emitter barrier, the emitter injection efficiency is improved substantially, so a very low offset voltage (

The dc performances of a novel InP-InGaAs tunneling emitter bipolar transistor (TEBT) are studied and demonstrated. The studied device can be operated under an extremely wide collector current regime larger than 11 decades in magnitude (10/sup -12/ to 10/sup -1/ A). A current gain of 3 is obtained even operated at an ultralow collector current of 3.9/spl times/10/sup -12/ A (1.56 /spl times/10/sup -7/ A/cm/sup 2/). The common-emitter and common-base breakdown voltages of the studied device are higher than 2 and 5 V, respectively. Furthermore, a very low collector-emitter offset voltage of 40 mV is found. The temperature-dependent dc characteristics of the TEBT are measured and studied. Consequentially, based on experimental results, the studied device provides the promise for low-power electronics applications.

DC characteristics of interesting In0.49Ga0.51P-channel heterostructure field-effect transistors (HFETs) with different gate metals, e.g., Pt, Pd and Au, have been studied and demonstrated. A very thin and fresh oxide layer is introduced to increase the gate turn-on and breakdown voltages and reduce the gate leakage current. It is found that, metal-oxide-semiconductor field-effect transistors show higher barrier height, turn-on voltage, breakdown voltage, off-state voltage, output current and transconductance than metal-semiconductor field-effect transistors. In addition, the barrier height and turn-on voltage are increased with the increasing metal work function. However, the breakdown voltage is decreased with the increasing metal work function. All studied devices show good performances of high breakdown voltage, high output drain saturation and flat and wide transconductance operation regimes. The temperature-dependent behaviours are also studied. It is known from experimental results that In0.49Ga0.51P HFETs show good potentiality in high-temperature electronics applications.

The high-performance n + -GaAs/p + -InGaP/n-GaAs high-barrier gate camel-like HFETs are successfully fabricated and demonstrated. The p + -InGaP layer is introduced to increase the barrier height and carrier confinement. Experimentally, good DC and AC device performances are obtained. For the studied 1×100 μm 2 device A (B), a gate–drain turn-on voltage of 1.6 (1.2) V, gate–drain breakdown voltage over 40 V with low leakage current of 400 (37) μA/mm, drain–source off-state breakdown voltage of 38 (39.7) V, maximum transconductance g m,max of 145 (147) mS/mm, unity current gain cut-off frequency f T of 17 (15) GHz, and maximum oscillation frequency f max of 33 (28) GHz are obtained, respectively, at room temperature. Moreover, the studied devices also show significantly wide and flat I DS operation regimes of g m , f T and f max .

The InP/InGaAs and InGaP/GaAs superlattice emitter resonant tunneling bipolar transistors (SE-RTBTs) have been fabricated and demonstrated. By the employment of five-period superlattice in the emitter layer, the RT effect in saturation regime is observed at 77 K for InP/InGaAs SE-RTBT. In addition, due to the larger valence band discontinuity ΔE V at InGaP/GaAs heterojunction, the RT effect is observed both in saturation and forward active regimes at 300 K for InGaP/GaAs SE-RTBT. The confinement effect for minority carriers is enhanced due to the insertion of superlattice. The common emitter current gains up to 170 and 220 are observed for InP/InGaAs and InGaP/GaAs SE-RTBTs, respectively. Lower offset voltages of about 125 mV are observed in the studied devices.

A new S-shaped switch based on the InP/InGaAlAs material system has been successfully fabricated and demonstrated. Due to the avalanche multiplication and potential redistribution process, the interesting multiple-negative-differential-resistance (MNDR) is found under the inverted operation mode at room temperature. The three-terminal NDR characteristics are investigated under the applied base current I B . Moreover, the anomalous multiple-route and multiple-step current-voltage (I-V) characteristics at 77K are also observed. The switching behaviors demonstrate that the proposed structure is a good candidate for multiple-valued logic applications.

We propose two InGaP/GaAs resonant tunneling bipolar transistors (RTBT's) with different superlattice (SL) structures in the emitters. Based on the calculations of transmission probability, the ground-state and first excited-state minibands are estimated. The electron transmission through SL structures is significantly determined by the electric field behaviors across the barriers. The specific designs of barrier width in the SL structures are responsible for two electron transport mechanisms of sequential RT conduction associated with the minibands. Experimentally, at higher current levels, the double- and quaternary-negative difference resistance (NDR) phenomena are respectively observed for both devices at 300K. Furthermore, the experimental results are in good agreement with the theoretical prediction.

A novel InP/InGaAs tunneling emitter bipolar transistor (TEBT) is fabricated and demonstrated. The studied device exhibits a very small collector-emitter offset voltage of 40 mV and an extremely wide operation regime. The operation region is larger than 11 decades in magnitude of collector current (10/sup -12/ to 10/sup -1/A). A current gain of 3 is obtained even if the device is operated at an ultralow collector current of 3.9 /spl times/ 10/sup -12/A (1.56 /spl times/ 10/sup -7/A/cm/sup 2/). Furthermore, the common-emitter breakdown voltage of the studied device is higher than 2 V. Consequently, the studied device shows a promise for low supply voltage, and low-power consumption circuit applications.

The DC performances of a novel InP/InGaAs double-heterojunction bipolar transistor (DHBT) with the undoped tunneling barrier and composite collector structure are studied and demonstrated. Due to the mass filtering effect for holes, a thin InP tunneling barrier can be used to replace the wide-gap emitter. Experimentally, an extremely small offset voltage of 25 mV and breakdown voltage BV/sub CEO/ of 9.2 V are obtained. Furthermore, the abrupt junction and /spl delta/-doping structure can eliminate the carrier blocking effect effectively when electrons are transported across the base-collector heterojunction. Meanwhile, the DC current gain is almost independent of the perimeter-to-area ratio of the emitter due to the low surface recombination.