Gummel plot

Abstract: The authors have demonstrated, for the first time, a functional Npn double heterojunction bipolar transistor using a novel material, InGaAsN, with a bandgap energy of 1.2 eV as the p-type base layer. A 300 /spl Aring/ thick In/sub x/Ga/sub 1-x/As graded layer was introduced to reduce the conduction band offset at the p-type InGaAsN base and n-type GaAs collector junction. For an emitter size of 500 /spl mu/m/sup 2/, a peak current gain of 5.3 has been achieved.

Abstract: N-p-n Al/sub 0.05/GaN/GaN heterojunction bipolar transistors with a common emitter operation voltage higher than 330 V have been demonstrated using selectively regrown emitters. Devices were grown by metalorganic chemical vapor deposition on sapphire substrates. The n-type emitter was grown selectively on a 100-nm-thick p-base with an 8 /spl mu/m n-collector structure using a dielectric mask. The shallow etch down to the collector mitigates damages induced in the dry etch, resulting a low leakage and a high breakdown. The graded AlGaN emitter results in a common emitter current gain of /spl sim/18 at an average collector current density of up to 1 kA/cm/sup 2/ at room temperature.

Abstract: A novel doping method called rapid vapor-phase direct doping (RVD) is developed to form ultra-shallow junctions. The base region of a conventional bipolar transistor is formed by this method, and in ultra-narrow 25-nm base is obtained. The Gummel plot of this device shows almost ideal characteristics. This result suggests that this method does not induce any defects which cause a leakage current. RVD is a thermal diffusion method using hydrogen as a carrier gas and B/sub 2/H/sub 6/ as a source gas. In this method, the impurity atoms directly diffuse from the vapor phase into silicon by a rapid thermal process without a boron-glass layer or metallic boron layer. By varying the source gas flow rate, doping time, and temperature, ultra-shallow junctions below 40 nm with controlled surface concentrations are successfully formed. An ultra-shallow 20-nm junction with surface boron concentration of 4*10/sup 18/ cm/sup -3/ is obtained at 800 degrees C for 5 min with B/sub 2/H/sub 6/ flow rate of 30 ml/min. >

Abstract: SiGe HBTs featuring a high quality oxide passivation show ideal Gummel plots and low 1/f noise with corner frequencies down to 300 Hz. The measured KB-factor of 2.6 × 10–10 µm2s is the lowest of any previously reported HBT. With an f⊤ of 40 GHz, the devices are ideal for low phase noise microwave oscillators. A simple 10 GHz microstrip resonator showed –100 dBc at 100 kHz off carrier.