High-speed GaInAs/InP multiquantum well avalanche photodiodes grownby atmospheric-pressure MOCVD

Reports the performance of the first high speed GaInAs/InP multi-quantum well avalanche photodiodes grown by atmospheric pressure MOCVD. The multi-quantum well avalanche region of the device consists of 50 periods of 150 Å wells and barriers forming the intrinsic region of a pin structure. Avalanche multiplication up to a factor of 25 has been measured at DC together with high-speed response giving a maximum measured RF gain of 16 and a gain-bandwidth product in excess of 25 GHz     

InP/InGaAs buried-structure avalanche photodiodes

Planar InP/InGaAs avalanche photodiodes with a new guardring structure have been designed and fabricated. The diodes had a buried n-InP layer and an n?-InP multiplication region under p-n junctions. A successful guardring effect was obtained. The diode exhibited a uniform multiplication over the active region, a maximum multiplication factor of 30, low dark currents of around 20 nA at 90% of breakdown voltage and a flat frequency response up to 1 GHz. Multiplication noise was measured up to a multiplication factor of 17.     

Excess noise in GaAs avalanche photodiodes with thin multiplicationregions

It is well known that the gain-bandwidth product of an avalanche photodiode can be increased by utilizing a thin multiplication region. Previously, measurements of the excess noise factor of InP-InGaAsP-InGaAs avalanche photodiodes with separate absorption and multiplication regions indicated that this approach could also be employed to reduce the multiplication noise. This paper presents a systematic study of the noise characteristics of GaAs homojunction avalanche photodiodes with different multiplication layer thicknesses. It is demonstrated that there is a definite “size effect” for multiplication regions less than approximately 0.5 μm. A good fit to the experimental data has been achieved using a discrete, nonlocalized model for the impact ionization process     

Excess noise analysis of separate absorption multiplication regionsuperlattice avalanche photodiodes

The operation of a separate absorption multiplication region avalanche photodiode (SAM-APD) introduces noise as results of randomness in the number and in the position at which dark carrier pairs are generated, randomness in the photon arrival number, randomness in the carrier multiplication, and the number and the position of the photogenerated carriers in the bulk of the diode. The dark current results in a smaller mean multiplication gain in excess noise factor versus mean multiplication plot due to the partial multiplication process of these generated carriers compared to the usual values associated with carriers injected at one edge of the diode. Previous analyses of mean multiplication and excess noise factor for an arbitrary superposition of injected carriers are extended to allow the presence of dark carriers in the multiplication region under the model, which admits variation (with position) of the band-gap, dark generated rate, and ionization coefficients with each stage for the superlattice APD, and the presence of impact ionization in the absorption region. The calculations reveal the presence of impact ionization carriers in the absorption region which results in a larger excess noise factor than the usual values associated with carriers injected at one edge of the device, and fits well with experimental results     

Double junction AlInAs/GaInAs multiquantum well avalanche photodiodes

A separate absorption, grading, and multiplication avalanche photodiode with an AlInAs/GaInAs multiquantum well multiplication region is reported. This device exhibits a low excess-noise factor and a gain-bandwidth product of 50 GHz, due to the high ratio of ionisation rates of the multiplication material. In addition, a large bandwidth is obtained owing to the use of an undoped (n type) GaInAs absorption layer, fully depleted when multiplication occurs.<>     

Epitaxial structures for InGaAs/InP avalanche photodiodes

The influence of parameters of the MOS hydride epitaxy on structural and electrophysical characteristics of InGaAs/InP heterostructures is studied experimentally. The chosen parameters are used to grow device structures and fabricate planar avalanche photodiodes based on them. The results of measuring of their photoelectrical properties suggest that the developed structures are suitable for fabrication of commercial planar avalanche photodiodes.     

Flip-chip planar GaInAs/InP p-i-n photodiodes analysis of frequencyresponse

High-speed response, high-manufacturing-yield photodiodes will be needed for optical interconnection in computer and for broadband networks. Frequency responses of a new planar GaInAs/lnP p-i-n photodiode for flip-chip bonding are analyzed. To study changes caused by the new structure, responses are related to device parameters including photoabsorption layer thickness, p-i-n junction diameter, and the size of the forward biased p-i-n junction. Forward biasing is a peculiarity of our photodiodes. A photodiode with an optimized design showed good characteristics     

Frequency response of InP/InGaAsP/InGaAs avalanche photodiodes

A theoretical model for the frequency response of InP/InGaAs avalanche photodiodes (APDs) is presented. Included in the analysis are resistive, capacitive, and inductive parasitics, transit-time factors, hole trapping at the heterojunction interfaces, and the avalanche buildup time. The contributions of the primary electrons, primary holes, and secondary electrons to the transit-time-limited response are considered separately. Using a measurement apparatus which consists of a frequency synthesizer and a spectrum analyzer controlled by a microcomputer, the frequency response of InP/InGaAsP/InGaAs APDs grown by chemical-beam epitaxy are measured. Good agreement with the calculated response has been obtained over a wide range of gains     

Vapour-grown 1.3 ?m InGaAsP/InP avalanche photodiodes

A novel planar InGaAsP/InP avalanche photodiode structure prepared by vapour-phase epitaxy is described. Avalanche gain up to 20 at 1.3 ?m and at reverse breakdown of 65 V has been measured.     

1.3 ?m InP/InGaAsP planar avalanche photodiodes

An InP/InGaAsP planar avalanche photodiode operating at a wavelength of 1.3 ?m has been fabricated by using Be implantation and a difference of impurity concentrations between two n-InP epitaxial layers. A sufficient guard ring effect is demonstrated by a photoresponse, and an avalanche gain of 110 is obtained at an initial photocurrent of 0.35 ?A.     

Low dark-current, high gain GaInAs/InP avalanche photodetectors

High performance inverted-mesa GaInAsP/InP avalanche photodiodes responding out to 1.25 μm have been fabricated. Uniform avalanche gainsM, of 700 dark-current densities of3 times 10^{-6}A/cm²atM = 10, and an excess noise factor of ∼3 atM = 10have been achieved by placing the p-n junction in the InP and using a new passivation technique. Pulse-response rise times of less than 160 ps, limited by the rise time of the mode-locked Nd:YAG laser pulse, were measured with an avalanche gain of 40.     

Investigation of microplasmas in InP avalanche photodiodes

The electron beam induced current technique has been used to investigate microplasmas in InP avalanche photodiodes. It is shown that microplasmas develop along growth induced doping striations. Slope discontinuities in the I-V characteristic have been correlated to the turn on voltage of microplasmas.     

The effect of nonuniform gain on the multiplication noise of InP/InGaAsP/ InGaAs avalanche photodiodes

We have investigated the effect of spatial gain uniformity on the multiplication noise of InP/InGaAsP/InGaAs avalanche photodiodes (APD's) with separate absorption, "grading," and multiplication regions. APD's with localized regions of high gain exhibit higher excess noise factors and poorer Performance in lightwave receivers than those with uniform gain.     

InP/InGaAsP avalanche photodiodes with new guard ring structure

A new guard ring structure for InP/InGaAsP avalanche photodiodes is described, which makes use of the impurity concentration difference between two InP epitaxial layers. The guard ring effect gives a low dark current and uniform multiplication characteristics at ? = 1.29 ?m.     

Monolithic integration of GaInAsP/InP carrier depletion directionalcouplers and GaInAs p-i-n detectors on semi-insulating InP

Monolithic integration of two optical switches consisting in carrier depletion directional couplers based on GaInAsP/InP double heterostructure waveguides, with two GaInAs p-i-n detectors has been realized on semi-insulating InP. Packaged devices based on 2 mm coupling length directional couplers exhibit a switching voltage of -15 V and a 3 dB cutoff frequency of 1.3 GHz. Also, total fiber-to-fiber insertion loss of only 16 dB is achieved without any antireflection coating     

Absolute noise characterisation of avalanche photodiodes

Excess noise in four types of commercially obtained avalanche photodiodes (a.p.d.s) has been measured absolutely, by comparing avalanche noise from the a.p.d. with shot noise from an illuminated p-i-n diode. The method used yields directly the noise-current spectral density, simplifies the deduction of the quantum efficiency keff and hence the true value of the multiplication factor, and ultimately yields a measured value of the noise parameter x.     

Multiplication noise in multi-heterostructure avalanche photodiodes

Using a multi-feedback network representation, multiplication noise in two-stage and three-stage heterostructure avalanche photodiodes has been calculated for different degrees of carrier feedback over heterobarriers. Results show appreciable dependence of noise on carrier feedback in III–V compound APD's, the effect being less with larger number of stages.     

High-speed InP/InGaAsP/InGaAs avalanche photodiodes grown bychemical beam epitaxy

High-performance InP/InGaAsP/InGaAs avalanche photodiodes (APDs) grown by chemical beam epitaxy are described. These APDs exhibit low dark current (less than 50 nA at 90% of breakdown), good external quantum efficiency (greater than 90% at a wavelength of 1.3 μm), and high avalanche gain (≃40). In the low-gain regime, bandwidths as high as 8 GHz have been achieved. At higher gains, a gain-bandwidth-limited response is observed; the gain-bandwidth product is 70 GHz     

High-speed InP/InGaAs avalanche photodiodes with a compositionallygraded quaternary layer

InP/InGaAs avalanche photodiodes (APDs) with a compositionally graded quaternary layer at the heterointerface between the InGaAs absorption and InP multiplication regions were fabricated and tested. A comparison of samples with the graded layer and with conventional three quaternary layers showed that the frequency characteristics for samples with the graded layer did not deteriorate at a low bias voltage even below -100°C, unlike APDs with three InGaAsP layers. Thus, no hole trapping occurred at the InP/InGaAs heterointerface with the graded layer. A sample with the graded layer showed a cutoff frequency exceeding 9 GHz at a low multiplication factor of 2. The authors found InP/InGaAs APDs with the compositionally graded quaternary layer to be useful over a wide temperature range     

InP/InGaAsP/InGaAs avalanche photodiodes grown by chemical beam epitaxy

InP/InGaAsP/InGaAs avalanche photodiodes with separate absorption, grading, and multiplication regions (SAGM-APD's) have been fabricated from wafers grown by chemical beam epitaxy (CBE). These APD's exhibit low dark current (<25 nA at 90 percent of breakdown), low capacitance (≈0.2 pF), and good responsivity (0.75 A/ W at 1.3 µm). The pulse response, which is relatively independent of avalanche gain, is characterized by rise and fall times of approximately 1.4 ns.