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A novel functional InGaP/GaAs/InGaAs step-compositional-emitter heterojunction bipolar transistor (HBT) is fabricated and demonstrated. Due to the avalanche multiplication and discontinuous confinement effects for electrons in the InGaAs quantum well and at InGaP/GaAs heterojunction, respectively, an interesting triple-route S-shaped negative-differential-resistance switch is observed under inverted operation mode at room temperature. In addition, the excellent transistor performances including a high current gain of 220 and a low offset voltage of 60 mV are achieved under normal operation mode. Consequently, the device could be used for signal amplifier under normal operation mode and multiple-valued logic circuit application under inverted operation mode.

In this paper, a functional InGaP/GaAs/InGaAs step-compositional-emitter heterojunction bipolar transistor (SCEBT) is demonstrated. The excellent transistor performance, including a high current gain and a low collector–emitter offset voltage, is achieved under normal operation mode. In particular, an interesting three-state S-shaped negative-differential-resistance (NDR) switch is observed under inverted operation mode at room temperature because of the reduction of base barrier height and discontinuous confinement effects for electrons in a InGaP/GaAs heterojunction and InGaAs quantum well, respectively. The three-terminal base-controlled NDR characteristics and multiple-valued logic applications are also investigated. Consequently, the transistor action and switching characteristics of the studied SCEBT are promising for signal amplifier and logic circuit applications.

A functional InGaP/GaAs double heterostructure-emitter bipolar transistor (DHEBT) is fabricated and demonstrated. Due to the large valence band discontinuity to conduction band discontinuity ratio at InGaP/GaAs heterojunction and the symmetrical structure, excellent transistor performances with a high current gain of 195 and a low collector–emitter (C–E) offset voltage of 60 mV are achieved. In particular, attributed to the avalanche multiplication and confinement effect for electrons at InGaP/GaAs heterojunction, an interesting multiple S-shaped negative-differential-resistance (NDR) switches is observed under large C–E forward voltage.

The authors demonstrate and compare the experimental results of the high-performance InGaP /InGaAs camel-gate n-channel and p-channel /spl delta/-doped pseudomorphic modulation-doped field effect transistors (pMODFETs). For the n-channel device, because of the p-n depletion in the camel-like gate region and the presence of large conduction band discontinuity at InGaP/InGaAs heterostructure, an extremely large gate turn-on voltage than 1.7 V is measured. However, the p-channel device exhibits a larger turn-on voltage than 2 V due to the relatively large valence band discontinuity at InGaP/InGaAs heterostructure.

In this article, high-performance InP/InGaAs heterostructure confinement bipolar transistors, including a /spl delta/-doped heterojunction bipolar transistor (5-HBT) and superlattice-confinement bipolar transistor (SCBT), are successfully fabricated and demonstrated.

An InP/InGaAs /spl delta/-doped pnp heterojunction bipolar transistor (HBT) has been successfully fabricated and demonstrated for the first time. The addition of a /spl delta/-doped sheet between two undoped spacer layers more effectively eliminates the potential spike at the emitter-base junction, lowers the emitter-collector offset voltage, and increases the effective barrier for electrons, simultaneously. A maximum current gain of 50 and a low offset voltage of 70 mV are obtained, respectively. To our knowledge, the offset voltage of the studied device is the best reported for InP/InGaAs pnp HBTs.

A functional InGaP/GaAs/InGaAs step-compositional-emitter heterojunction bipolar transistor (HBT) is fabricated and demonstrated. Due to the avalanche multiplication and discontinuous confinement effects for electrons at InGaP/GaAs heterojunction and InGaAs quantum well, an interesting triple-route S-shaped negative-differential-resistance switch is observed under inverted operation mode at room temperature. In addition, the excellent transistor performances including a high current gain of 220 and a low offset voltage of 60 mV are achieved under normal operation mode. Consequently, the excellent switching characteristic and transistor action of the studied HBT provides a promise for amplifier and multiple-valued logic circuit applications.

A high-performance InGaP/InGaAs/GaAs p-channel pseudomorphic modulation-doped field effect transistor based on p/sup +/-GaAs/n/sup +/-InGaP/p-InGaP camel-like gate structure is demonstrated. Due to the p-n depletion of the camel-like gate and the presence of relatively large /spl Delta/Ev at InGaP/InGaAs heterostructure, an extremely large gate turn-on voltage than 2 V is measured. For a 1/spl times/100 /spl mu/m/sup 2/ device, the experimental results show a maximum saturation current density of -345 mA/mm and a widely broad gate voltage swing than 4 V with 80 % maximum transconductance. Furthermore, the f/sub T/ and f/sub max/ values are 3.1 and 4.8 GHz, respectively.

In this article, high-performance InGaP∕InGaAs∕GaAs δ-doped pseudomorphic modulation-doped field effect transistors (pMODFETs) employing n+-GaAs∕p+-InGaP∕n-InGaP camel-gate structure are characterized. Because of the depleted p-n junction in the gate region and the presence of the large conduction-band discontinuity of the InGaP∕InGaAs heterostructure, a large gate turn-on voltage is obtained. The dc and microwave characteristics of single- and double-δ-doped pMODFETs are demonstrated. The double-δ-doped pMODFET exhibits a higher drain saturation current, a larger transconductance, a broader gate voltage swing, and better high-frequency responses than the single-δ-doped device. The excellent performance of the studied devices is promising for linear and large signal amplifiers and high-frequency circuit applications.

A novel InGaP/InGaAs/GaAs p-channel pseudomorphic modulation-doped field effect transistor based on p+-GaAs/n+-InGaP/p-InGaP camel-like gate structure is reported for the first time. Owing to the p–n depletion of the camel-like gate and the presence of relatively large ΔEv at InGaP/InGaAs heterostructure, an extremely large gate turn-on voltage, greater than 2 V, is measured. For a 1×100 µm2 device, the experimental results show a maximum saturation current density of −345 mA/mm and a widely broad gate voltage swing, greater than 4 V, with 80% maximum transconductance. Furthermore, the fT and fmax values are 3.1 and 4.8 GHz, respectively.