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The reliability of high-speed SiGe:C HBT under electrical stress close to the Safe Operating Area (SOA) limit is analyzed and modeled. A long time stress test, up to 1000 h, is performed at bias conditions chosen according to applications targeted for these transistors. During the aging tests, Gummel plots are measured at fixed time to analyze the evolution of base and collector current. At low level injection, we observed an increase of the base current whereas the collector current remains constant for the whole Vbe range and during the 1000 h aging time. By means of 2D TCAD simulations, this evolution of base current is attributed to trap activity at the emitter-base junction periphery. Based on TCAD simulation results, we propose an aging law using a differential equation that has been implemented in HiCUM L2 v2.33. This reliability-aware compact model allows designers creating reliability-aware circuit architectures at an early stage of the design procedure, well before real circuits are actually fabricated. � 2015 Elsevier Ltd.

The passivation mechanisms and qualities of Al2O3, SiNx, SiO2 and a-Si:H( i ) on p - and n -type silicon are investigated by quasi-steady-state photoluminescence measurements. This technique allows effective lifetime measurements in an extremely large injection range between 1010 cm-3 and 1017 cm-3. The measurements are discussed focusing on injections below 1012 cm-3 in order to determine the most effective passivation layer for solar cells arranged for indoor applications. Fixed negative charges in the passivation layer cause field-effect passivation due to band bending leading to either accumulation or inversion at the passivation layer/silicon interface. Accumulation causes a stable passivation quality at low level injection. Inversion leads to effective lifetime losses similar to the losses in the space charge region. On p -type silicon the most effective surface passivation at low injections is provided by Al2O3 or a-Si:H( i ). The n -type silicon samples passivated with a-Si:H( i ) show the best effective lifetimes. SiNx and SiO2 show lifetimes one order of magnitude below a-Si:H( i ). Al2O3 on n -type is the most effective passivation at high injections around 1015 cm-3. Due to inversion losses at low level injections the passivation quality decreases more than two orders of magnitude for injections around 1010 cm-3.

The paper deals with a current-controlled non-equilibrium process, whereby the influx of minority carriers into a semiconducting material is smaller than the rate required for normal conduction in the undisturbed, homogeneous bulk. It is shown, within the framework of a “small signal theory”, how the corresponding concentration and field contours depend on the carrier lifetime, the mobility ratio and the current composition contact characteristics (via the exclusion ratio). The departures from electronic equilibrium can lead to a total resistance increase or a decrease, depending on the detailed combination of parameters.