Arkady Gavrilov

Experimental evidence for the correlation between the weak inversion hump and near midgap states in dielectric/InGaAs interfaces

Temperature dependent capacitance–voltage (C-V) and conductance-voltage (G-V) measurements were performed to obtain activation energies (EA) for weak inversion C-V humps and parallel conductance peaks in Al2O3/InGaAs and Si3N4/InGaAs gate stacks. Values of 0.48 eV (slightly more than half of the band gap of the studied In0.53Ga0.47As) were obtained for EA of both phenomena for both gate dielectrics studied. This indicates an universal InGaAs behavior and shows that both phenomena are due to generation-recombination of minority carriers through near midgap located interface states. The C-V hump correlates with the interface states density (Dit) and can be used as a characterization tool for dielectric/InGaAs systems.

Indium outdiffusion and leakage degradation in metal/Al2O3/In0.53Ga0.47As capacitors

Annealing of Ni/Al2O3/InGaAs structures results in a significant increase of the leakage current. The same treatment of Au/Ti/Al2O3/InGaAs structures results in a slight increase in leakage only. Time of flight secondary ions mass spectrometry measurements detected an annealing induced indium outdiffusion into the dielectric layer. In structures having nickel metallization, the released indium accumulated at the Ni/Al2O3 interface. In structures having Au/Ti metallization, the indium atoms penetrated into the gold layer, and an indium free Al2O3 layer was observed. We attribute the observed different electrical behavior to the different indium diffusion behavior, and eliminate other explanations.

Correlation between Ga-O signature and midgap states at the Al2O3/In0.53Ga0.47As interface

Al2O3/In0.53Ga0.47As gate stacks were fabricated using different concentrations of NH4OH as a pre-deposition treatment. Increased NH4OH concentrations significantly reduced the C-V weak inversion hump and the measured near midgap interface states density (Dit). X-ray photoelectron spectroscopy (XPS) studies revealed that these changes in the electrical properties were accompanied by a reduction in the amount of the Ga-O bonding while As-As dimers as well as other XPS detected InGaAs surface species did not correlate with the observed Dit trend. Possible explanations for these findings are suggested.

Resistive Switching in

Resistive switching in thin HfO2 films is studied using a metal-insulator-semiconductor bipolar transistor structure. Using this structure, electron injection into the semiconductor valence band can be distinguished from injection into the conduction band. In addition, the p-n junction serves as a sensitive detector of damage induced by the switching effect. The implications of the obtained experimental results on the validity of various conduction mechanisms through the insulator are discussed.

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Indium phosphide nanowires were grown by metalorganic molecular beam epitaxy using the selective-area vapor-liquid-solid method. We show experimentally and theoretically that the size of the annular opening around the nanowire has a major impact on nanowire growth rate. In addition, we observed a considerable reduction of the growth rate in dense two-dimensional arrays, in agreement with a calculation of the shadowing of the scattered precursors. Due to the impact of these effects on growth, they should be considered during selective-area vapor-liquid-solid nanowire epitaxy.

Probed by a Metal–Insulator–Semiconductor Bipolar Transistor

We report on the performance of abrupt InP-GaInAs-InP double heterojunction bipolar transistors (DHBTs) with a thin heavily doped n-type InP layer at the base-collector interface. The energy barrier between the base and the collector was fully eliminated by a 4-nm-thick silicon doped layer with N/sub D/=3/spl times/10/sup 19/ cm/sup -3/. The obtained f/sub T/ and f/sub MAX/ values at a current density of 1 mA//spl mu/m/sup 2/ are comparable to the values reported for DHBTs with a grade layer between the base and the collector.

Shadowing and mask opening effects during selective-area vapor?liquid?solid growth of InP nanowires by metalorganic molecular beam epitaxy

The temperature dependence of the current-voltage characteristics of Ni-InGaAs alloy Schottky contacts to n-In0.53Ga0.47As was measured. Nearly ideal plots with an ideality factor close to unity were obtained. The Arrhenius curve across the wide temperature range of 80–300 K was perfectly linear, yielding a barrier height of 0.239 ± 0.01 eV. This value is substantially larger than previously reported. Conventional metal based Schottky diodes did not exhibit an ideal Schottky behavior. The ideal Schottky diode characteristics are attributed to the lack of oxidation and contamination of the interface between Ni-InGaAs and InGaAs.

An abrupt InP-GaInAs-InP DHBT

An indium phosphide heterojunction bipolar transistor (InP HBT) oscillator chip was monolithically integrated with an on chip p-i-n photodiode. A controllable locking range was obtained in unidirectional injection locking. High-purity optoelectronic oscillator with parasitic modes lower than -4 dBc resulted from bidirectional injection locking. The optoelectronic oscillator power consumption was 50 mW while providing output power of - 2 dBm . The overall chip size is 1.3 times 0.8 mm.

Measurement of the Schottky barrier height between Ni-InGaAs alloy and In0.53Ga0.47As

We present an InP HBT distributed amplifier with a bandwidth of 75 GHz, gain of 14 dB, and power consumption of 78 mW. The HBTs had a 600 nm thick collector, and hence relatively low fT and fMAX of 84 GHz and 150 GHz respectively. The thick collector is a tradeoff required in optoelectronic integrated receivers, in which the PIN diode layers are the same as the base collector layers. To obtain high PEN diode responsivity, the collector layer needs to be thicker than in optimized HBTs. The amplifier topology comprises an emitter follower at the input and a cascode stage, with a resistor and inductance at the emitter follower output, and a peaking line between the HBTs in the cascode stage. The amplifier exhibits matching at the input better than -10 dB up to 85 GHz. The chip contains 16 HBTs and it size is 1.7mm times 0.9 mm

An InP HBT-Based Oscillator Monolithically Integrated With a Photodiode

The dc current gain of InP-GaInAs heterojunction bipolar transistors with varying base thickness and composition was measured. Much larger composition grade values than previously reported were achieved using strain compensation. A simple two-parameter Monte Carlo simulation was developed to interpret the results. The simulation yields an accurate plot of the base transit time versus base thickness. Clear evidence for the reduction of base transit time due to hot electron injection was observed in devices with thin uniform bases. The current gain of 45-nm-thick graded base devices saturated as the grading was increased beyond standard values. Grading did not increase the gain of devices with a 20-nm-thick base.