Improvement of SiGe oxide grown by electron cyclotron resonance using H2O vapor annealing

The influence of low-temperature annealing in H2O vapor on electron-cyclotron-resonance (ECR) grown SiGe oxides is reported. Annealing the oxides in H2O vapor at 280°C for 3 h 20 min, applied after annealing in forming gas at 450°C for 30 min, has several important effects: It reduces oxide leakage current by up to four orders of magnitude, decreases the density of interface states, and results in a low fixed oxide charge density of - 5.0× 1010 cm-2 in comparison to those of the films subjected to annealing in forming gas only. In addition, higher cumulative dielectric breakdown fields up to 8 MV/cm have been achieved. From the results obtained it is evident that vapor annealing is beneficial for ECR-grown SiGe oxides. © 1996 American Institute of Physics.published_or_final_versio

Integration of GaInP/GaAs heterojunction bipolar transistors and high electron mobility transistors

Integration of carbon-doped GaInP/GaAs heterojunction bipolar transistors (HBT's) and high electron mobility transistors (HEMT's) is demonstrated by growing an HBT on the top of a HEMT. A current gain of 60. a cutoff frequency of 59 GHz and a maximum oscillation frequency of 68 GHz were obtained for a 5 × 15 μm 2 self-aligned HBT. The HEMT with a gate length of 1.5 μm has a transconductance of 210 mS/mm, a cutoff frequency of 9 GHz and a maximum oscillation frequency of 22 GHz. It is shown that the GaInP/GaAs HBT on the HEMT is the simple Bi-FET tecnology suitable for microwave and mixed single applications.published_or_final_versio

A self-aligned structure AlGaAs/GaAs HBT's using silicon nitride sidewall technique

A self-aligned fabrication process for AlGaAs/GaAs heterojunction bipolar transistors (HBT's) is presented. The advantage of this process is that selfaligned structure and device passivation can be realized simultaneously using silicon nitride sidewall technique. The silicon nitride sidewall functions both as an isolation layer to prevent shorting between the base metal and the emitter mesa and as an etching mask to prevent AlGaAs passivation layer to be removed. A current gain cutoff frequency fT of 30 GHz and a maximum oscillation frequency fmax of 50 GHz have been obtained from the device with 3 μm×15 μm emitter size.published_or_final_versio

Avalanche multiplication and ionization coefficient in AlGaAs/InGaAs p-n-p heterojunction bipolar transistors

The hole-initiated impact ionization multiplication factor Mp -1 and the ionization coefficient αp in AlGaAs/InGaAs p-n-p heterojunction bipolar transistors are presented. A large departure is observed at low electric field when comparison is made between the measured data and those obtained from avalanche photodiode measurements. The results show that the conventional impact ionization models, based on local electric field, substantially overestimate the hole impact ionization multiplication factor Mp -1 and the hole ionization coefficient in p-n-p heterojunction bipolar transistors where significant dead space effects occur in the collector space charge region.published_or_final_versio

Thermal effect on current gains of an AlGaAs/GaAs heterostructure-emitter bipolar transistor

The temperature dependence of current gain was investigated for AlGaAs/GaAs heterostructure-emitter bipolar transistors (HEBT). The current gain of the HEBT was found much less sensitive to temperature variation than that of a heterojunction bipolar transistor. In particular, the HEBT current gain was more or less constant with increasing temperature at the high current regime, indicating great potentials for power applications.published_or_final_versio

CCl4-doped semi-insulating InP as a buffer layer in GaInAs/InP high electron mobility transistors

The application of CCl4-doped semi-insulating InP as a buffer layer in a pseudomorphic Ga0.2In0.8P/Ga0.47In0.53As/InP high electron mobility transistor (HEMT) grown by metalorganic chemical vapor deposition is reported. This Al-free InP-base HEMT with a gate length of 1.3 μm has extrinsic transconductances of 420 and 610 mS/mm at 300 and 77 K, respectively. A cutoff frequency of 15 GHz and a maximum oscillation frequency of 40 GHz are obtained. The results demonstrate the CCl4-doped semi-insulating InP is a promising buffer layer for InP-based HEMT. © 1996 American Institute of Physics.published_or_final_versio

A high-frequency GaInP/GaAs heterojunction bipolar transistor with reduced base-collector capacitance using a selective buried sub-collector

A C-doped GaInP/GaAs HBT using a selective buried sub-cellular has been fabricated by two growth steps. The device was fabricated with minimum overlap of the extrinsic base reduced to about half of that of an HBT without selective buried sub-collector while the base resistance remains unchanged. A current gain of 35, f T of 50 GHz and f max of 140 GHz are obtained with this technology.published_or_final_versio

Dead space effect in space-charge region of collector of AlGaAs/InGaAs p-n-p heterojunction bipolar transistors

Hole-initiated avalanche multiplication is investigated using an AlGaAs/InGaAs p-n-p heterojunction bipolar transistor (HBT). Both experimental measurements and theoretical calculation are used to determine the avalanche multiplication factor. A large departure is observed at low electric field when comparison is made between the measured data and theoretical results obtained from the standard ionization model. The comparison shows that the conventional impact ionization model, based on local electric field, substantially overestimates the hole avalanche multiplication factor Mp - 1 in the AlGaAs/InGaAs p-n-p HBT, where a significant dead space effect occurs in the collector space-charge region. A simple correction model for the dead space is proposed, that allows the multiplication to be accurately predicted, even in a heavily doped structure. Based on this model, multiplication characteristics for different threshold energy of the hole are calculated. A threshold energy of 2.5 eV was determined to be suitable for describing the hole-initiated impact ionization process. © 2001 American Institute of Physics.published_or_final_versio

Implementation of CMRC on HBT power amplifier for WCDMA application

An InGaP/GaAs heterojunction bipolar transistor (HBT) is developed. By using this HBT, a power amplifier is designed for WCDMA user equipment, band-1 power class-2 application. The HBT power amplifier demonstrates a maximum output power (Pout) of 29.4dBm and a PAE of 48% at the frequency of 1.95GHz. When it operates in WCDMA standard, it achieves a Pout of 27dBm and a PAE of 32.4%. The Adjacent Channel Leakage power Ratio (ACLR) is -33dBc. To further improve the PAE, ACLR and IM3 performance, a CMRC circuit has been implemented on the HBT amplifier. The effect of CMRC on PAE and ACLR is investigated using a low power HBT amplifier. The results show that the ACLR can be improved by the CMRC. © 2004 IEEE.published_or_final_versio

A functional magnetic resonance imaging study comparing brain activations during language task with activations during electrical stimulation of language-implicated acupoints

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