Zn Diffusion Technique Research Articles

Optical properties of Zn-diffused InP layers for the planar-type InGaAs/InP photodetectors * * Project supported by the Key R&D Program of Jiangsu Province (No. BE2016085) , the National Natural Science Foundation of China (Nos. 61674051), and the External Cooperation Program of BIC, Chinese Academy of Sciences (No. 121E32KYSB20160071).

Zn diffusion into InP was carried out ex-situ using a new Zn diffusion technique with zinc phosphorus particles placed around InP materials as zinc source in a semi-closed chamber formed by a modified diffusion furnace. The optical characteristics of the Zn-diffused InP layer for the planar-type InGaAs/InP PIN photodetectors grown by molecular beam epitaxy (MBE) has been investigated by photoluminescence (PL) measurements. The temperature-dependent PL spectrum of Zn-diffused InP samples at different diffusion temperatures showed that band-to-acceptor transition dominates the PL emission, which indicates that Zn was commendably diffused into InP layer as the acceptor. High quality Zn-diffused InP layer with typically smooth surface was obtained at 580 °C for 10 min. Furthermore, more interstitial Zn atoms were activated to act as acceptors after a rapid annealing process. Based on the above Zn-diffusion technique, a 50 μm planar-type InGaAs/InP PIN photodector device was fabricated and exhibited a low dark current of 7.73 pA under a reverse bias potential of −5 V and a high breakdown voltage of larger than 41 V (I < 10 μA). In addition, a high responsivity of 0.81 A/W at 1.31 μm and 0.97 A/W at 1.55 μm was obtained in the developed PIN photodetector.

Fabrication and passivation of GaSb photodiodes

A novel Zn diffusion technique in n-GaSb substrate from a low temperature chemical bath deposited ZnS layer has been developed to obtain high breakdown voltages. Junctions formed by this technique have breakdown voltages of ∼18.5V, low reverse leakage current (0.01–0.03A/cm2 at -3V), excellent reverse current saturation and ideality factor of ∼1.3. The high breakdown voltages obtained are due to the co-doping of zinc and sulfur from the ZnS film. Sulfur forms shallow and deep levels that compensate the p-doping of zinc. The non-linear relation of the inverse of the zero-bias resistance area product (1/R0A) versus perimeter to area ratio (P/A) in these diodes indicates surface leakage is the dominant leakage mechanism. CdS has been used to passivate the mesa photodiodes. After passivation, the 1/R0A product reduces from 0.3 to 0.02Ω-1cm-2 for a 150μm diameter device. The 1/R0A product is also independent of the diode dimension confirming effective passivation. ZnS surface passivation on the mesa walls is not effective and is found to increase the leakage current.

Minimization of Damping in the Electrooptic Frequency Response of High-Speed Zn-Diffusion Single-Mode Vertical-Cavity Surface-Emitting Lasers

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> We utilize the Zn-diffusion technique to fabricate a single-mode high-speed 850-nm vertical-cavity surface- emitting laser. With this technique, we are able to minimize the thermal effect without greatly scaling down the diameter of the oxide- confined aperture. The demonstrated device has a 9-<emphasis><formula formulatype="inline"> <tex>$\mu$</tex></formula></emphasis>m active diameter with which we can attain a bandwidth of 8 GHz, a small differential resistance (<emphasis><formula formulatype="inline"><tex>$\sim$</tex></formula></emphasis>47 <emphasis><formula> <tex>$\Omega$</tex></formula></emphasis>), and a maximum output power of 3 mW. The single-mode characteristics can be sustained under dynamic operation for the whole bias current range. The dynamic measurement results indicate that with this single-mode device the damping-limited bandwidth of our multimode control can be eliminated without a Zn-diffusion aperture. A larger intrinsic bandwidth (32 versus 21 GHz) is also obtained due to the minimization of damping. The narrower divergence angle (8<emphasis><formula formulatype="inline"><tex>$^{\circ}$</tex> </formula></emphasis> versus 20<emphasis><formula formulatype="inline"><tex>$^{\circ}$</tex> </formula></emphasis>) means that the device exhibits a larger alignment tolerance and much lower coupling loss (9 dB) when used with the standard multimode fiber than those of the control sample. </para>

Vertical-cavity surface-emitting lasers (VCSELs) with high-power and single-spot far-field distributions at 850-nm wavelength by use of petal-shaped light-emitting apertures

In this letter, we demonstrate a vertical-cavity surface-emitting laser (VCSEL) with a petal-shaped light-emitting aperture, which is realized by the Zn-diffusion technique, at a wavelength of 850 nm. The demonstrated device behaves like a two-dimensional VCSEL array and each light-emitting unit can have high coherence of in-phase lasing to form a near fundamental supermode emission. The measured far-field distributions of such a device exhibit single-lobe (spot), high-power (>7.5 mW), and narrow divergence angle (~6deg) performance under a wide range of bias current. The ratio of in-phase lasing mode to total lasing modes, which include isolated single mode, in-phase, and out-of-phase modes, has also been analyzed by the measured far-field distributions and the theoretically calculated patterns

Single-mode vertical-cavity surface-emitting laser with ring-shaped light-emitting aperture

In this letter, we demonstrate a single-mode vertical-cavity surface-emitting laser (VCSEL) with a ring-shaped light-emitting aperture, which is realized by the Zn diffusion technique, at a wavelength of 850nm. Relative to the control VCSEL with an ordinary circular aperture and the same geometry and size, the demonstrated device can suppress the higher-order transverse mode more effectively without affecting the threshold current and output power. Compared with typical reported single-mode VCSELs, a larger light-emitting aperture and current-confined area with a smaller divergence angle of the output beam, and lower differential resistance are achieved with the present structure.

Continuous-wave laser operation at 1.3 μm in Nd3+-doped Zn:LiNbO3 channel waveguides

This work reports continuous laser action around 1.3 μm at room temperature in LiNbO3:Nd3+ channel waveguides, fabricated by the two-steps Zn diffusion technique. A threshold of 64 mW and a slope efficiency of around 0.5% were obtained in an 8 μm wide channel guide. These results have been compared with laser oscillation around 1.08 μm in LiNbO3:Nd3+ waveguides in terms of the launched pump powers, taking into account the emission cross section values of the F3/24→4I13/2 and F3/24→4I11/2 transitions.

Blue Light by SHG in Diode Pumped LiNbO3 Waveguides

In this work, second harmonic generation (SHG) in nonlinear channel waveguides by quasi phase matching is reported. The photorefractive damage resistant waveguides were fabricated by Zn-diffusion technique using periodic poled lithium niobate wafers (PPLN). The SH wave, at 397.8 nm, was generated by using a CW diode laser with emission wavelength at 795.6 nm and 1 W peak power was used as fundamental wave. The nonlinear waveguides exhibit a stable conversion even at room temperature with no sign of deterioration induced by the optical damage.

Photorefractive Damage Resistant Zn-Diffused Optical Waveguides in LiNbO 3 : Nd 3+ and Laser Operation

This work reports the fabrication of photorefractive damageresistant channel waveguides by a two-step Zn-diffusion technique in LiNbO 3 :Nd 3+ crystals and the demonstration of laser operation at room temperature at u =1.085 w m.

Buried p -gate heterojunction field effecttransistor

A buried p+-AlGaAs gate AlGaAs/InGaAs/AlGaAs double heterostructure field effect transistor (FET) (p-gate HFET) operating in enhancement mode has been successfully fabricated using the Zn-diffusion technique. A low on-resistance of 1.6 Ωmm and a high gate built-in voltage of 1.5 V with a maximum transconductance of 420 mS/mm were obtained for a 0.8 µm gate device. The buried p-gate HFET is promising for power-FET applications which require low distortion, high efficiency and positive bias operation.

Wide-wavelength and low-dark-current lattice-mismatched GaInAs photodiodes

A lattice-mismatched GaInAs photodiode with low dark current and very wide-wavelength spectral response has been fabricated on InP substrate. The uses of a lattice-mismatched GaInAs light-absorbing layer and a very thin InP cap layer provide extended responsivity for longer and shorter wavelengths, respectively. To improve the crystal quality of the lattice-mismatched GaInAs layer a strained-superlattice buffer layer was used, with a combined thermal cycle annealing process, resulting in a low dark current. The shallow pn junction of the photodiode was formed by a newly developed Zn diffusion technique.

Optoelectronic properties of gallium antimonide light emitting diodes

Gallium antimonide light emitting diodes operating at room temperature were fabricated by a Zn diffusion technique. Their electrical and spectral properties were investigated and related to the band structure of the material. The peak electroluminescence emission wavelength was found to depend both on the LED drive current and the diffusion conditions used to produce the p-n junction. Longer diffusion periods resulted in diodes which emitted at shorter wavelengths.

Metal‐p+‐n Enhanced Schottky Barrier Structures on (100) InP

An in vacuo, shallow Zn diffusion technique has been examined for increasing the effective Schottky barrier height of Ag and Au on (100) . For a single diffusion cycle, a barrier enhancement of ∼0.1 eV was achieved by forming a shallow (∼400Å) p+ layer with an acceptor‐to‐bulk‐donor ratio . A multiple diffusion sequence yielded barrier enhancements of ∼0.2 eV for a p+ layer width of ∼800Å and . Numerical evaluation of Poisson's equation, including both electron and hole free‐carrier densities, provides estimates of where the depletion approximation fails as a function of doping and width of the surface p+ layer.

Zn-diffused In0.53Ga0.47As/InP avalanche photodetector

Mesa In0.53Ga0.47As avalanche photodetectors were successfully fabricated by liquid-phase-epitaxial growth on (100) -InP substrate and Zn-diffusion technique. An avalanche multiplication M as high as 32 was measured under broad-area illumination provided by a cw InGaAsP laser at 1.3 μm. Distribution of M was measured by an electron-beam-induced current image of a scanning electron microscope, and uniform multiplication profiles were observed up to M=3 and M=12 at the mesa diameter of 300 and 150 μm, respectively.

Ga(AsP) light-emitting diode formed by ion implantation

Hot ion implantation as a doping technique was used for the fabrication of visible-light-emitting diodes with GaAs1−xPx(x = 0.38 ± 0.01). Zinc ions, p-type dopants, were implanted into n-type (001)-oriented heteroepitaxially grown Ga(AsP)-on-GaAs substrates at 400°C with an energy of 20 keV. Then, thermal treatment at various temperatures was carried out on the sample in order to investigate the effect of annealing on the electrical properties of Zn-implanted layers in the Ga(AsP) substrate. The p-type layer, which was obtained by the ion implantation of 2 × 1015 Zn ions/cm2 with subsequent annealing at 900°C for 40 min, was found to have an effective surface concentration of 1.7 × 1015 carriers/cm2 and a sheet resistivity of about 100 Ω/sq. Red-light-emitting Ga(AsP) diodes fabricated using Zn ion implantation have usually shown an average brightness of 400–600 fL, and sometimes as high as 850 fL at a current density of 10 A/cm2. Diodes, which were formed by means of a standard Zn diffusion technique in an evacuated ampoule at 750°C for 30 min using a ZnAs2 source, had an average brightness of 350–500 fL at the same current density.