Planar PIN Research Articles

Time-Dependent Ginzburg-Landau Simulation of Critical Current Density Including z-axis Anisotropy

In this study, the three-dimensional time-dependent Ginzburg-Landau equations were numerically solved to visualize the motion of the flux lines in a superconductor under a transverse magnetic field. Pins were inserted into a superconducting rectangular parallelepiped, and the magnetic field dependence of the normalized critical current density Jc was calculated. Anisotropy y_Z of different magnitudes was introduced along the direction of the magnetic field (z-axis). Different pin shapes and orientations were also considered: columnar pins aligned parallel to the direction of either the magnetic field or the current flow, spherical pins, and a planar pin in the field-current plane. For the columnar pins aligned parallel to the field (along the flux lines), J c showed almost no dependence on y_Z. Additionally, a peak in the Jc -B c urve for this pin geometry was observed at normalized magnetic field, B= 0.4 for all considered y_z. In contrast, J c was dependent on y_Z for the columnar pins aligned parallel to the current flow (perpendicular to the flux lines) and the spherical pins. At low magnetic fields (B= 0.1), J c increased with increasing y_Z in both these cases. In the case of the planar pin, J c showed no dependence on y_Z. In conclusion, when a pin was inserted parallel to the normalized magnetic field B, Jc did not decrease even when the z-axis anisotropy y_Z was large.

3D GaN-based betavoltaic device design with high energy transfer efficiency

A combined GaN 3D core-shell and planar pin structure is being developed and demonstrated to achieve the highest potential to increase energy transfer efficiency from the source (ηsrc) and power generated per cm2 (PGaN/cm2) in a betavoltaic (BV) device configuration. Physics-based Sentaurus TCAD and Monte Carlo N-Particle extended (MCNPX) software are employed to obtain the maximum ηsrc and PGaN/cm2 by a parametric study of device dimensions coupled with a 63NiCl2 source. Idealized structure dimensions are determined to be 2 µm wide, 4 µm tall GaN pin core-shell mesas, with 63Ni source conformally surrounding the structure with a 2 µm gap for maximum efficiency of energy transfer. For maximizing power deposited (10 µm mesa separation) a 3.75x increase in PGaN/cm2 at approximately half the activity density compared to a planar device is achieved for 4 µm mesa height, with 5.82x improvement in ηsrc.

Visualization and suppression of interfacial recombination for high-efficiency large-area pin perovskite solar cells

The performance of perovskite solar cells is predominantly limited by non-radiative recombination, either through trap-assisted recombination in the absorber layer or via minority carrier recombination at the perovskite/transport layer interfaces. Here, we use transient and absolute photoluminescence imaging to visualize all non-radiative recombination pathways in planar pin-type perovskite solar cells with undoped organic charge transport layers. We find significant quasi-Fermi-level splitting losses (135 meV) in the perovskite bulk, whereas interfacial recombination results in an additional free energy loss of 80 meV at each individual interface, which limits the open-circuit voltage (VOC) of the complete cell to ~1.12 V. Inserting ultrathin interlayers between the perovskite and transport layers leads to a substantial reduction of these interfacial losses at both the p and n contacts. Using this knowledge and approach, we demonstrate reproducible dopant-free 1 cm2 perovskite solar cells surpassing 20% efficiency (19.83% certified) with stabilized power output, a high VOC (1.17 V) and record fill factor (>81%). Non-radiative recombination is a critical limiting factor for perovskite solar cell performance. Stolterfoht et al. visualize the various recombination pathways in planar pin cells with photoluminescence imaging and use it to design improved solar cells with 1 cm2 areas and ~20% efficiency.

Electrical and photo-stimulated characteristics of all-implanted CMOS compatible planar Si photodiode

A scheme consisted of all-implantation processed planar silicon PIN Photodiode is fabricated and characterized to evaluate and optimise its potential for photo detection applications. Current Voltage, Capacitance Voltage and Photo-Simulated Internal Field Transient Characteristics are presented to check the compatibility of the design device with the CMOS manufacturing process routines, as well as the efficiency of the process. The effect of the variety of light intensities incident on the devices on the physical characteristic is also evaluated and analyzed. Presence of short-span photovoltaic effect is also witnessed in the transient analysis.

New PIN diode structure for neutron dose measurement

Planar silicon PIN diodes have been proposed as neutron dosimeters before. In this paper, a new structure of planar silicon PIN diode with ring shaped backside n+ doping is proposed. Simulation shows effective improvement in the current distribution compared with a normal planar PIN structure. Diodes with different lateral spaces between p+ and n+, i.e., 200–500 μm, were fabricated. The sensitivity of the diodes to neutron irradiation was measured. The dependence of the sensitivity on the working current of the diode was analyzed. The impact of the lateral space on the diode sensitivity was investigated. The results show that the sensitivity of the diode is proportional to the square root of the current at high-level injection and increases with the lateral space between the p+ and n+ regions.

A 2D Full-Band Monte Carlo Study of HgCdTe-Based Avalanche Photodiodes

This work presents a numerical simulation study of HgCdTe-based avalanche photodetectors (APDs). The two-dimensional model used is based on a full-band Monte Carlo approach in which the electronic structure is computed using a nonlocal empirical pseudopotential model with spin–orbit corrections. The carrier–phonon scattering rates have been computed from first principles using a rigid pseudo-ion model. The most attractive feature of these devices is the potential for single-carrier ionization when electrons are used as the primary injection carrier. For this reason, this work focuses on two front-illuminated (electron-injection) device structures: a planar diffused PIN structure and a planar diffused PN photodiode with guard rings. To predict the performance of these APDs, the electron multiplication gain has been studied as a function of the position where photogenerated carriers are injected and as a function of the curvature of the p-type diffusion region. We find that, in the diffused PIN structure, the limited lateral spatial extent of the high-electric-field region leads to a reduction of the multiplication gain from the center of the device to the periphery. Furthermore, the higher the curvature, the more abruptly the gain decreases. For the simple PN structure, we find that the presence of the guard rings removes the high electric field from the surface and induces a more gradual roll-off of the gain from the center of the device to the periphery.

Evaluation of pixellated, back-sided planar photodetectors for high-resolution imaging instrumentation

Future generations of solid-state high-energy gamma imaging cameras require pixellated semiconductor photodetectors with the greatest possible detection efficiency. In this paper, a new type of planar silicon PIN photodiode is presented, in which both p+ and n+ electrodes are located on the same side of the device. The design offers highly efficient optical coupling between the backside and scintillator, providing a fill factor of close to 100%. The performance of this detector is modelled using the ISE-TCAD simulator and its electrical and spectroscopic characteristics are experimentally investigated for the case of direct interaction of ionising radiation and also with an attached CsI(Tl) scintillator. The energy resolutions obtained at room temperature (21∘C) at 662keV (scintillated) and 27keV (direct) were 6.3% and 7.0% respectively, measured at full width at half maximum (FWHM). The new detector can be easily manufactured into arrays, for a variety of imaging (instrumentation) applications.

Low-cost photoreceiver integrating an EDWA and waveguide PIN photodiode for 40 Gbit/s applications

A novel low-cost photoreceiver that combines an erbium-doped waveguide amplifier (EDWA) and a packaged short planar multimode waveguide PIN photodiode has demonstrated −21.2 dBm sensitivity at BER 10−10 and PRBS of 215−1 for 40 Gbit/s operations.

Overlapping Shockley/Frank Faults in 4H-SiC PiN Diodes

Using light emission imaging (LEI), we have determined that not all planar defects in 4H-SiC PiN diodes expand in response to bias. Accordingly, plan-view transmission electron microscopy (TEM) observations of these diodes indicate that these static planar defects are different in structure from the mobile stacking faults (SFs) that have been previously observed in 4H-SiC PiN diodes. Bright and dark field TEM observations reveal that such planar defects are bounded by partial dislocations, and that the SFs associated with these partials display both Frank and Shockley character. That is, the Burgers vector of such partial dislocations is 1/12<4-403>. For sessile Frank partial dislocations, glide is severely constrained by the need to inject either atoms or vacancies into the expanding faulted layer. Furthermore, these overlapping SFs are seen to be fundamentally different from other planar defects found in 4H-SiC.

Ultra high performance planar InGaAs PIN photodiodes for high speed optical fiber communication

This paper reports a front-illuminated planar InGaAs PIN photodiode with very low dark current, very low capacitance and very high responsivity on S-doped InP substrate. The presented device which has a thick absorption layer of 2.92 μm and a photosensitive area 73 μm in diameter exhibited the high performance of a very low capacitance of 0.47 pF, a very low dark current of 0.041 nA, a very high responsivity of 0.99 A/W (79% quantum efficiency) at λ = 1.55 μm, the 3 dB bandwidths of 6.89 GHz (−5 V), 7.48 GHz (−12 V) for bare chips and 4.48 GHz (−5 V), 5.02 GHz (−12 V) for the devices packaged in TO can, respectively. Furthermore, the developed PIN photodiodes possess high breakdown voltage of less than −25 V.

Theoretical study of top illuminated planar SiC PIN ultraviolet detectors

AbstractIt is the first time that the idea of planar PIN structure ultraviolet (UV) detection has been demonstrated on SiC EPI wafers. By using this structure, the surface illuminated device has no efficiency‐bandwidth trade‐off problem, also can be easily integrated as an array device which can solve the low signal issue in normal edge illuminated device due to small device area with no sacrificial of high bandwidth. The performance of SiC PIN photodetectors is analyzed based on a serial of process parameters and device structures. The calculated results show the correlations of dark current, photocurrent, bandwidth (BW) with PIN structures and fabrication processes. Speed and optoelectronics performances were carefully considered for real implementations under theoretical conditions. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Fabrication of very high quantum efficiency planar InGaAs PIN photodiodes through prebake process

The fabrication is reported of large-area (73 μm in diameter) front-illuminated planar InGaAs PIN photodiodes on S-doped InP substrates through the prebake process and investigations are made of various Zn diffusion times on a 2.9-μm thick absorption layer. As a result of the best tuning of the Zn diffusion time, the large-area planar InGaAs PIN photodiodes achieve a lowest capacitance of 0.43 pF, a lowest dark current of 39 pA, a highest responsivity of 0.99 A/W (79% quantum efficiency) at λ=1.55 μm, and a highest 3-dB bandwidth of 6.98 GHz for a bare chip and 4.53 GHz for the device packaged in a TO can, respectively. Furthermore, the developed PIN photodiodes possess high breakdown voltage (less than −25 V) and provide the P and N electrodes located at different sides of the photodiodes, thus improving the devices for easy bonding and packaging.

Zn doping of InP, InAsP/InP, and InAsP/InGaAs heterostructures through metalorganic vapor phase diffusion (MOVPD)

Zinc incorporation by post-growth metalorganic vapor phase diffusion (MOVPD) is used to achieve high p-doping, which is desirable for the fabrication of photodiodes. Diethylzinc (DEZ) is used as precursor and Zn is diffused into InP and InAs0.6P epitaxial layers grown by low pressure metalorganic vapor phase epitaxy (MOVPE) on different substrate orientations, enabling the investigation of the dislocation density on the Zn incorporation. Diffusion depths are measured using cleave-and-stain techniques, resistivity measurements, electrochemical profiling, and secondary ion mass spectroscopy. High hole concentrations of, respectively, 1.7 1019 and 6 1018 cm−3, are obtained for, respectively, InAs0.60P and InP. The diffusion coefficients are derived and the Zn diffusion is used for the fabrication of lattice-mismatched planar PIN InAsP/InGaAs photodiodes.

Investigation of the peak shape parameter of CdZnTe detectors

There is a need to define the magnitude of the asymmetry of the peak shapes (the tailing fraction) of CdTe and CdZnTe detectors. Since this tailing parameter determines to a large extent, the performance of peak fitting programs used to extract the peak areas from gamma spectra taken for the verification of nuclear material, a well-defined knowledge of this parameter is an important factor in such programs. The magnitude of the asymmetry of this tailing fraction was investigated for different models of CdTe and CdZnTe detectors. The gamma peak analysis program PkCheck (R. Gunnink, R. Arlt, Proceedings of 11th International Workshop on room temperature Semiconductor X- and gamma-ray detectors and associated electronics, 11–15 October 1999, Vienna, Austria, Nucl. Instr. and Meth. A 485 (2001) 196, This issue) was used to determine the tailing fraction as a function of detector type, high voltage and other operational parameters. Although there are considerable individual differences between different detector units of the same model, a general trend towards the growing of the tailing fraction with increasing detector volume was clearly observed. The lowest fractions are observed for electrically cooled planar pin CdTe detectors operated with a charge loss corrector, followed by small size hemispheric CdZnTe detectors.

Zinc diffusion in InAsP/InGaAs heterostructures

A systematic study of the sealed ampoule diffusion of zinc into epitaxially grown InP, In0.53Ga0.47As, In0.70Ga0.30As, In0.82Ga0.18As, and through the InAsP/InGaAs interface is presented. Diffusion depths were measured using cleave-and-stain techniques, electrochemical profiling, and secondary ion mass spectroscopy. The diffusion coefficients, \(D = D_o e^{ - E_a /kT} \), were derived. For InP, D0=4.82 × 10−2cm2/sec and Ea=1.63 eV and for In0.53Ga0.47As, D0=2.02 × 104cm2/sec and Ea=2.63 eV. Diffusion into the heteroepitaxial structures used in the fabrication of planar PIN photodiodes is dominated by the effects of the InP/InGaAs interface.

Temperature-humidity-bias-behavior and acceleration model for InP planar PIN photodiodes

The reliability of InP planar PIN photodiodes in humid ambients has been studied. The dependence of the degradation rate in temperature, humidity and bias was determined by aging devices at temperatures between 50 and 150/spl deg/C, humidities between 50 and 85% RH, and biases between 2 and 25 V. Failure occurred as a result of a sudden increased dark current. This increase in dark current had little affect on the device responsivity. At all aging conditions the failure distributions were well represented by a lognormal distribution in time with a dispersion of less than 0.3. From these data, an acceleration factor (AF) was developed and is given by AF=exp(E/kT)exp[A(RH)/sup 2/]exp[B(V)] where E=-0.42 eV, A=-4.6/spl times/10/sup -4/, and B=-6.7/spl times/10/sup -2//V. Extensive failure mode analysis was done on more then 500 failed devices. Based on this, a failure mechanism was proposed. The model requires ingress of moisture to the InP surface. The moisture is reduced at the p-contact region of the device region, giving off hydrogen. Under negative bias In and P react with the hydrogen to form gaseous IH and PH/sub 3/. This lead to the semiconductor erosion. The erosion continues until device failure occurs. The worst case concentrate of PH/sub 3/ which if created would produce less than 0.1 ppb PH/sub 3/ per cm/sup 3/ of air. Thus it is not a fire or health hazard. Finally, we present reliability prediction for nonhermetic PIN's encapsulated in an optically clear silicone based polymer. We estimate a 20 year hazard rate of less than 100 FIT's for devices operating at an ambient of 45/spl deg/C/50% RH. For comparison, the hermetic counterparts of similar design have a 20 year hazard rate of less than 10 FIT's.

New profiled silicon PIN photodiode for scintillation detector

Silicon photodiodes (planar PIN) are employed for the readout of scintillation shower counters. We have already reported on a new doping method called molecular layer doping (MLD) which has been developed for very large scale integrated (VLSI) technologies. In this study, several types of PIN photodiodes, in which a p/sup +/ layer was formed by MLD (MLD-PIN) or BF/sub 2/ ion implantation (BF/sub 2/ I/I-PIN), have been examined. The MLD-PIN has a shallow p/sup +/ junction depth (x/sub j/) with sufficient high surface concentration, and simply and easily provides good performance for short-wavelength photosensitivity. >

8×8 flipchip assembled InGaAs detector arrays for optical interconnect

The design and performance of detector arrays for optical interconnect are reported. These arrays consist of an InGaAs/InP heterostructure planar pin photodiode with optical access through the substrate. A selfaligned flipchip solder bond assembly process has been used to provide mechanical attachment and direct electrical connection to an electrical backplane or silicon integrated circuit. Arrays with up to 64 elements have been fabricated with mean dark current densities of 500 nA cm−2, with assembly yields in excess of 99.85% and submicrometre alignment accuracy.

The Determination of the Probabilistic Properties of Velocities and Accelerations in Kinematic Chains With Uncertainty

A probabilistic model and methods to determine the means and variances of the velocity and acceleration within stochastically-defined planar pin jointed kinematic chains are presented. The presented model considers the effect of tolerances on link length and radial clearance and uncertainty of pin location as a net effect on the link’s effective length. The determination of the mean values and variances of the output variables requires the calculation of sensitivities of secondary variables with respect to the random variables. It is shown that this computation is straightforward and can be accomplished by a conventional kinematic analysis package. Thus, the concepts of tolerance and clearance have been captured by the model and analysis. The only input data is the nominal linkage model and statistical information. The “effective link length” model is shown to be applicable to both analytical solution and Monte Carlo simulation. The results from both methods are compared. This paper solves the higher-order kinematics problem for the probabilistic design analysis of stochastically defined mechanisms.

Reliability of mesa and planar InGaAs PIN photodiodes

InGaAs planar-structure PIN photodiodes fabricated from MOVPE material have been demonstrated to have outstanding reliability. The predicted random failure rate at 20 degrees C is less than 0.3 FITs, and the mean time to failure is estimated to be 10/sup 11/ hours at 20 degrees C. By contrast, the reliability of mesa-structure photodiodes is unacceptable because of an instability of the dark current. A similar kind of instability has been observed in commercially available mesa photodiodes. Extensive life testing of planar-structure and mesa-structure PINs made by several manufacturers shows that the reliability of mesa-structure PINs is inferior in all cases.< >