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In this paper an annealing procedure which gives an excess noise reduction both of heavily C-doped resistive structures and GaInP/GaAs Heterojunction Bipolar Transistors (HBTs) of 5 dB is proposed. The investigation of the correlation between the noise generators indicate that the annealing leads to a decrease of noise voltage attributed to a strai...
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Context 1
... Fig. 3, we have reported the frequency evolution of the input noise voltage generator for #A and #B2 samples. The spectra result as for TLM structures from the superimposition of both low 1/f noise and a strong g-r noise (see the bump on the spectra). Furthermore the experimental data show that device (#A) is noisiest than device #B2 which indicate that annealing produces a reduction of the input noise voltage generator magnitude. This opposite behavior with respect to the noise current indicate that the physical mechanisms which produce noise voltage and noise current are probably ...
Context 2
... Fig. 4, we have plotted the frequency evolution of the correlation coefficient between the noise voltage and noise current generators both for #A and #B2 device. The result first indicate that the correlation between the noise generators is poor (less than 30%) which is consistent with noise voltage generated in the resistive parts of the device (emitter and base) which has been previously observed in AlGaAs/GaAs HBT's [12]. The data indicate a correlation coefficient increasing with the annealing procedure which is consistent with a decrease of the noise voltage in the extrinsic base layer (see Fig. 3). The investigation of the correlation resistance which is related to the distributed base resistance [13] for #A and #B2 HBT's and which is defined by the ratio between the real part of the correlation between the input noise voltage and noise current generators and the input noise current generator [14] indicate that this correlation resistance is lower for #A sample than for #B2 one which denotes an increase of the distributed base resistance. We note an opposite behavior with respect to DC TLM measurements (where the resistance values equal to 235 are unchanged by annealing) which is related to the fact that HBT structure is different than TLM one. In fact the noise in the intrinsic base layer which is free of SiN is reduced through a site switching effect which leads to an increase of the intrinsic base resistance. The noise reduction in the extrinsic base layer which is SiN capped is related both to a C-H de-bonding and site switching ...
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InGaP/GaInAsN double heterojunction bipolar transistors (HBTs) with compositionally graded bases are presented which exhibit superior dc and radio frequency performance. Reducing the average base layer energy gap and optimizing the emitter-base (e-b) and base-collector (b-c) heterojunctions leads to a 100-mV reduction in the turn-on voltage compare...
The hole multiplication factor in pnp InAlAs/InGaAs single heterojunction bipolar transistors (HBTs) has been measured as a function of the base-collector bias. The hole impact ionization coefficient /spl beta//sub p/ has been estimated taking into account the Early effect, I/sub CBO/, and thermal effects. Numerical corrections for dead space were...
We report In P / In <sub>0.53</sub> Ga <sub>0.47</sub> As / In P double heterojunction bipolar transistors (DHBTs) with implanted subcollectors. We demonstrate the compensation of charge at the regrowth interface by the use of a blanket Fe implant. An isolated N<sup>++</sup> subcollector is then formed by a patterned Si implant. With the compensati...
Typically, the microwave power characteristics of InP/InGaAs SHBTs
have not been addressed due to their relatively inferior DC
characteristics when compared to DHBTs, which implies early breakdown
and thus limited power performance. On the other hand, SHBTs are very
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heterojuncti...
We demonstrate how, using electroluminescence, the parameters characterizing the recombination center induced by irradiation in a solar cell can be measured. Because electroluminescence is able to provide information on an individual cell in a multijunction (MJ) cell device, independently of the others, we apply this technique to measure these para...
Citations
Fabrication and structure-based hybrid-π small signal modeling of a submicron InGaP/GaAs heterojunction bipolar transistor (HBT) are discussed. The submicron InGaP/GaAs HBTs were fabricated using electron-beam lithography. The emitter mesa was realized by using H3PO4-based and NH4OH-based wet etching solutions. The fabricated submicron InGaP/GaAs HBTs had an emitter area of 0.5 × 2 µm 2 and emitter-base spacings of 0.25 µm, 0.85 µm, 2 µm, and 4 µm. The extracted maximum oscillation frequencies (fmax) of the submicron InGaP/GaAs HBTs having emitter-base spacings of 0.25 µm, 0.85 µm, 2 µm, and 4 µm were 222.5 GHz, 167.5 GHz, 69.3 GHz, and 41 GHz, respectively, at Ic = 1 mA and Vce = 2 V.
We report the result of investigation on hydrogen effects on GaInP/GaAs HBT structures originating from different MOCVD and CBE suppliers. It is demonstrated that hydrogen gives rise to initial unstable electrical behaviour by cross-examination of samples with and without hydrogen either intrinsically or by thermal-assisted removal. Annealing conditions to remove hydrogen have been optimized on the basis of SIMS analyses and Gummel plot characteristics to control eventual degradation of the junctions. It has been found that under particular doping and growth conditions, C2H complexes can be formed. These defects appear more stable than CH complexes which may explain the difficulty to remove hydrogen from some epitaxial layers.
This work deals with the short and long term effects of a current stress performed at room temperature on Carbon doped GaInP/GaAs heterojunction bipolar transistors. The investigation has been carried out by means of DC characterizations and low frequency noise (LFN) measurements in the 250 Hz–100 kHz frequency range. During the stress the devices were biased in the forward active region; a collector–emitter voltage of 7.7 V and a collector current density of 2.2×104 A/cm2 were imposed. The effect of the stress on the DC and LFN characteristics were compared and discussed in terms of two recombination mechanisms. The discussion points out that both extrinsic and intrinsic recombination processes have to be taken into account in order to justify the short and long term effects of the electrical stress.
Photoluminescence (PL) investigation was carried out on GaInP/GaAs multiple quantum wells structures grown on (001) and (311) B surfaces of GaAs by gas source molecular beam epitaxy. Superlattice structures of GaAs/GaInP grown on (001) GaAs substrate were also studied in comparison. Deep-level luminescence was seen to dominate the PL spectra from the quantum wells and superlattice structures that were grown on (001) GaAs substrate. In contrast, superior optical properties were exhibited in the same structures grown on (311) B GaAs surfaces. The results suggested that GaAs/GaInP quantum well structures on (311) B oriented substrates could efficiently suppress the deep-level emissions, result in narrower PL peaks indicating smooth interfaces. © 1998 American Institute of Physics.
InP based HBT's for circuit applications were fabricated on MOMBE
grown HBT layers. The layer structure included an InP emitter, InGaAs
base, and InP collector. A C-doped base was employed for excellent
device stability. The emitter-base and base-collector heterojunctions
were both graded with InGaAsP layers for better electrical
characteristics. An emitter-base self-aligned process was employed with
dry etch and wet chemical etch mesa isolations. For base contacts,
Pd/Zn/Pt/Au ohmic contacts were placed on top of the InGaAsP graded
layer between the emitter and base, and made to diffuse into the base
layer using rapid thermal annealing. This method produces an
emitter-base junction buried under the InGaAsP graded layer and helps
increase device reliability and life time. The device showed about 3%
degradation in DC characteristics when stressed at a collector current
density (J<sub>c</sub>) of 100 kA/cm<sup>2</sup> and collector bias of 2
V at room temperature for 360 hours. Typical common emitter current gain
was 40. f<sub>t</sub> of 78 GHz and f<sub>max</sub> of 129 GHz were
achieved for 3×5 μm<sup>2</sup> emitter size devices. Maximum f
<sub>t</sub> was achieved at 70 kA/cm<sup>2</sup> collector current
density and 2.25 V collector bias. f<sub>t</sub> decreased to 70 GHz at
130 kA/cm<sup>2</sup> collector current density. F<sub>max</sub>
decreased for longer emitter size devices (3×10 and 3×15
μm<sup>2</sup>) while f<sub>t</sub> maintained comparable
values
As the wireless communications of voice, video and data grows, the
increasing demand of channels and bandwidth is driving the transceiver
systems toward millimeter-wave frequencies. Noise performance of active
devices represent a key issue of the electronic systems since at low
frequencies 1/f noise and generation-recombination noise degrade the
spectral,purity of the micro-wave oscillator while high frequencies
noise can limit the performances of both the low-noise amplifier and the
mixer. During past years heterojunction bipolar transistors (HBTs) have
demonstrated attractive capabilities in terms of low-noise
millimeter-wave performance. Many efforts were focused on the noise
behavior versus material system, geometry device, bias and temperature
in order to state, on the well suited technology for low-noise
transceiver. In this paper, we propose to present a state of the art of
noise properties of micro-wave HBT's. Section II of the paper describes
the low-frequency (LF) and high frequency (HF) noise characterization
methods. Section III outlines a summary of previous works on excess
noise and high frequency noise modeling in HBTs. Section IV addresses a
brief description of the material used for HBT devices and their
corresponding electrical performances. Section V and VI deal with the LF
and HF noise properties of HBTs and finally, the conclusions are
presented in section VII
