We have investigated the total dose effects of 100
MeV Oxygen ion irradiation on the <i>dc</i> electrical characteristics
of Silicon-Germanium Heterojunction Bipolar Transistors (SiGe
HBTs). The results of oxygen ion irradiation were compared
with Co-60 gamma irradiation in the same total dose range (1
Mrad to 100 Mrad). The results show that even after 100 Mrad
of total dose, the degradation in the electrical characteristics of
SiGe HBT is acceptable from the circuit design point of view.
We present an investigation of low-frequency noise in advanced vertical <i>pnp</i> bipolar junction transistors (BJTs) with
differing interfacial oxide thicknesses (10Å, 12Å, and 14Å). Low-frequency noise is observed to exhibit a cubic
dependence on IFO thickness. Devices were measured across the temperature range of 90 K to 450 K. From 90 K to 250
K, the magnitude of the low-frequency noise is found to decrease with temperature, but from 250 K to 450 K the noise
actually increases with temperature. Devices were hot-carrier (electrically) stressed, and the low-frequency noise was
found to be almost unchanged with the addition of stress-induced traps. The transparency fluctuation model is suggested
as a possible explanation for the operative noise mechanism, due to the similar dependence of base current and low-frequency
noise on interfacial oxide thickness.
We report, for the first time, the low frequency noise characteristics of both fully- and partially-depleted SiGe HBTs-on-
SOI, both in forward and inverse modes of operation. These SiGe HBTs on thin-film SOI are then compared with bulk
SiGe HBTs in order to evaluate how the fundamentally different device structure affects 1/f noise performance. In
addition, the impact of substrate voltage, collector doping, and temperature on low-frequency noise is investigated.
We present a comprehensive investigation of the fundamental differences in low frequency noise behavior between <i>npn</i> and <i>pnp </i>SiGe HBTs. Geometry effects on the low frequency noise are assessed, as well as the impact of interfacial oxide(IFO) thickness on <i>pnp</i> noise characteristics. Temperature measurements and ionizing radiation are used to probe the fundamental physics of 1/f noise in<i> npn</i> and <i>pnp</i> SiGe HBTs. The<i> npn </i>transistors show a stronger size dependence than the <i>pnp</i> transistors. The 1/f noise for <i>pnp</i> SiGe HBTs exhibits an exponential dependence on IFO thickness, indicating that IFO produces the main contribution. In most cases, the magnitude of the 1/f noise has quadratic dependence on the base current(I<sub>B</sub>), the only exception being for the post-radiation <i>npn</i> transistor biased at low base currents, which exhibits a near-linear dependence on I<sub>B</sub>. In the proton radiation experiments, the <i>pnp</i> devices show better radiation tolerance than the <i>npn </i>devices. The observed temperature dependence for both types is quiet weak, consistent a tunneling mechanism.
SiGe technology represents a remarkable success story for the microelectronics industry, and possesses the capability to
fundamentally reshape the way broadband communications systems are conceived and built in the 21st century. From the first demonstration of a functional SiGe HBT in 1987, until the achievement of the present performance record of 375 GHz peak cutoff frequency, a mere 18 years has elapsed! The SiGe HBT is the first practical bandgap-engineered Si device, and has evolved from simple transistor and circuit demonstrations in a select few research laboratories to robust production in upwards of two-dozen manufacturing facilities around the world in 2005, and commercial products abound across a wide
spectrum of commercial applications. This paper reviews the state-of-the-art in SiGe technology, discusses the design and operational principles of SiGe HBTs, and then focuses on the broadband and low-frequency noise characteristics of SiGe HBTs, emphasizing both the opportunities and the challenges which will necessarily be faced with continued device scaling.
We present a comprehensive study of low-frequency noise mechanisms in 210 GHz SiGe HBTs using a variety of measurement techniques, and explain a unique scaling effect. The implication of these noise mechanisms on SiGe HBT compact modeling methodologies are also discussed.