Steven C. Moss

Observation of single event upsets in analog microcircuits

Selected analog devices were tested for heavy-ion-induced single event upset (SEU). The results of these tests are presented, likely upset mechanisms are discussed, and standards for the characterization of analog upsets are suggested. The OP-15 operational amplifier, which was found to be susceptible to SEU in the laboratory, has also experienced upset in space. Possible strategies for mitigating the occurrence of analog SEUs in space are also discussed. >

Correlation of picosecond laser-induced latchup and energetic particle-induced latchup in CMOS test structures

We show that the thresholds for picosecond (psec) laser pulse-induced latchup and energetic particle-induced latchup are well correlated over a range of bulk CMOS test structures designed to be susceptible to latchup. The spatial length of the latchup-sensitive node of the test structures covers a range of values that commonly occur in bulk CMOS devices. The accuracy of this correlation implies that laser-induced latchup can be used for hardness assurance and, under the proper conditions, can be an accurate predictor of latchup threshold linear energy transfer (LET) for most bulk CMOS devices.

Single event upset (SEU) sensitivity dependence of linear integrated circuits (ICs) on bias conditions

The single event upset (SEU) sensitivity of certain types of linear microcircuits is strongly affected by bias conditions. For these devices, a model of upset mechanism and a method for SEU control have been suggested.

Comparison of SETs in bipolar linear circuits generated with an ion microbeam, laser light, and circuit simulation

Generally good agreement is obtained between the single-event output voltage transient waveforms obtained by exposing individual circuit elements of a bipolar comparator and operational amplifier to an ion microbeam, a pulsed laser beam, and circuit simulations using SPICE. The agreement is achieved by adjusting the amounts of charge deposited by the laser or injected in the SPICE simulations. The implications for radiation hardness assurance are discussed.

Laser-induced and heavy ion-induced single-event transient (SET) sensitivity measurements on 139-type comparators

We have measured the single-event transient (SET) response for a number of 139-type comparators with differing topologies. In this paper, we present the results from pulsed laser measurements on a number of different 139-type devices, as well as heavy ion measurements on a new RM139 device from NSC. Devices tested with the laser included the HS-139RH, PM139, LM139 and a more recent version of LM139 from NSC. We discuss the effects of different device topologies on SET sensitivity. Our results agree qualitatively with SPICE model calculations of LM139s by Johnston et al.

Narrow band gap (1 eV) InGaAsSbN solar cells grown by metalorganic vapor phase epitaxy

Heterojunction solar cell structures employing InGaAsSbN (Eg ∼ 1 eV) base regions are grown lattice-matched to GaAs substrates using metalorganic vapor phase epitaxy. Room temperature (RT) photoluminescence (PL) measurements indicate a peak spectral emission at 1.04 eV and carrier lifetimes of 471–576 ps are measured at RT from these structures using time-resolved PL techniques. Fabricated devices without anti-reflection coating demonstrate a peak efficiency of 4.58% under AM1.5 direct illumination. Solar cells with a 250 nm-thick InGaAsSbN base layer exhibit a 17% improvement in open circuit voltage (Voc), 14% improvement in fill factor, and 12% improvement in efficiency over the cells with a thicker (500 nm-thick) base layer.

Catastrophic Facet and Bulk Degradation in High Power Multi-Mode InGaAs Strained Quantum Well Single Emitters

Extensive investigations by a number of groups have identified catastrophic sudden degradation as the main failure mode in both single-mode and multi-mode InGaAs-AlGaAs strained quantum well (QW) lasers. Significant progress made in performance characteristics of broad-area InGaAs strained QW single emitters in recent years has led to an optical output power of over 20W and a power conversion efficiency of over 70% under CW operation. However, unlike 980nm single-mode lasers that have shown high reliability operation under a high optical power density of ~50MW/cm2, broad-area lasers have not achieved the same level of reliability even under a much lower optical power density of ~5MW/cm2. This paper investigates possible mechanisms that prevent broad-area lasers from achieving high reliability operation by performing accelerated lifetests of these devices and in-depth failure mode analyses of degraded devices with various destructive and non-destructive techniques including EBIC, FIB, and HR-TEM techniques. The diode lasers that we have investigated are commercial MOCVD-grown broad-area strained InGaAs single QW lasers at ~975nm. Both passivated and unpassivated broad-area lasers were studied that yielded catastrophic failures at the front facet and also in the bulk. To investigate the role that generation and propagation of defects plays in degradation processes via recombination enhanced defect reaction (REDR), EBIC was employed to study dark line defects in degraded lasers, failed under different stress conditions, and the correlation between DLDs and stress levels is reported. FIB was then employed to prepare TEM samples from the DLD areas for cross-sectional HR-TEM analysis.

Analysis of transient photoluminescence measurements on GaAs and AlGaAs double heterostructures

The analysis of transient photoluminescence measurements and extraction of carrier recombination lifetimes in GaAs and AlGaAs double heterostructures is discussed. In contrast to recently reported claims, it is demonstrated that even in regions where the measured decay curves show single exponential behavior, the slopes do not, in general, correspond to any single physical carrier lifetime such as the minority‐carrier lifetime. A series of measurements over a range of incident optical intensities is required to extract such lifetimes.

Root cause investigation of catastrophic degradation in high power multi-mode InGaAs-AlGaAs strained quantum well lasers

Optimization of broad-area InGaAs-AlGaAs strained-quantum-well lasers has led to successful demonstration of high power and high efficient operation for industrial applications. State-of-the-art broad-area single emitters show an optical output power of over 20W and a power conversion efficiency of over 70% under CW operation. However, understanding of long-term reliability and degradation processes of these devices is still poor. This paper investigates the root causes of catastrophic degradation in broad-area lasers by performing accelerated lifetests of these devices and failure mode analyses of degraded devices using various techniques. We investigated MOCVDgrown broad-area strained InGaAs-AlGaAs single QW lasers at ~975nm. Our study included both passivated and unpassivated broad-area lasers that yielded catastrophic failures at the facet and also in the bulk. Our accelerated lifetests generated failures at different stages of degradation by forcing them to reach a preset drop in optical output power. Deep-level-transient-spectroscopy (DLTS) was employed to study deep traps in degraded devices. Trap densities and capture cross-sections were estimated from a series of degraded devices to understand the role that point defects and extended defects play in degradation processes via recombination enhanced defect reaction. Electron-beam-induced-current (EBIC) was employed to find correlation between dark line defects in degraded lasers and test stress conditions. Time-resolved electroluminescence (EL) was employed to study formation and progression of dark spots and dark lines in real time to understand mechanisms leading to catastrophic facet and bulk degradation. Lastly, we present our physics-of-failure-based model of catastrophic degradation processes in these broad-area lasers.

Impact of thermal annealing on bulk InGaAsSbN materials grown by metalorganic vapor phase epitaxy

Two different thermal annealing techniques (rapid thermal annealing (RTA) and in-situ post-growth annealing in the metalorganic vapor phase epitaxy (MOVPE) chamber) were employed to investigate their impact on the optical characteristics of double-heterostructures (DH) of InGaAsSbN/GaAs and on the performance of single-junction solar cell structures, all grown by MOVPE. We find that an optimized RTA procedure leads to a similar improvement in the photoluminescence (PL) intensity compared with material employing a multi-step optimized anneal within the MOVPE reactor. Time-resolved photoluminescence techniques at low temperature (LT) and room temperature (RT) were performed to characterize the carrier dynamics in bulk InGaAsSbN layers. Room temperature carrier lifetimes were found to be similar for both annealing methods, although the LT-PL (16 K) measurements of the MOVPE-annealed sample found longer lifetimes than the RTA-annealed sample (680 ps vs. 260 ps) for the PL measurement energy of 1.24 eV. InGaAsSbN-based single junction solar cells processed with the optimized RTA procedure exhibited an enhancement of the electrical performance, such as improvements in open circuit voltage, short circuit current, fill factor, and efficiency over solar cells subjected to the in-situ MOVPE annealing technique.