Low -temperature preparation of ZnO films on Si substrates by MOCVD

ZnO films were deposited on Si（100） substrates at 300℃ by metal - organic chemical vapor deposition（MOCVD）. The effect of different ratios of DEZn to N2O on crystal quality was analyzed. It is found that the optimum ratio of DEZn to N2O is 2.1. And in this optimum growth condition, X - ray diffraction （XRD） and scanning probe morphology （SPM） images indicate that the films grow along the c - axis orientation. ZnO film exhibits a strong UV optical absorption near 388 nm. And the optical absorbance is close to zero,that indicates nearly 100% optical transparence. Photoluminescence （PL） spectrum shows only strong near - band - edge emissions with little or no deep - level emission related to defects. The full - width at half - maximum （FWHM） of the ultraviolet emission peak is 80meV. The results indicate that better crystal quality can be obtained.

Fabrication of 1.55μm Si-Based Resonant Cavity Enhanced Photodetectors

A novel bonding method using silicate gel as bonding medium is developed.High reflective SiO2/Si mirrors deposited on silicon substrates by e-beam deposition are bonded to the active layers at a low temperature of 350℃ without any special treatment on bonding surfaces.The reflectivities of the mirrors can be as high as 99.9%.A Si-based narrow band response InGaAs photodetector is successfully fabricated,with a quantum efficiency of 22.6% at the peak wavelength of 1.54μm,and a full width at half maximum of about 27nm.This method has a great potential for industry processes.

Fabrication of SiGe/Si Multi-Quantum Wells Resonant-Cavity-Enhanced Detector

A SiGe/Si multi-quantum wells resonant-cavity-enhanced(RCE) detector with high reflectivity bottom mirror is fabricated by a new method.The bottom mirror is deposited in the hole,which is etched from the backside of the sample by ethylenediamine-pyrocatechol-water(EPW) solution with the buried SiO2 layer in SOI substrate as the etching-stop layer.Reflectivity spectrum indicates that the mirror deposited in the hole has a reflectivity as high as 99% in the range of 1.2～1.5μm.The peak responsivity of the RCE detector at 1.344μm is 1.2mA/W and the full width at half maximum is 12nm.Compared with the conventional p-i-n photodetector,the responsivity of RCE detector is enhanced 8 times.

1.3μm Si-Based MOEMS Optical Tunable Filter with a Tuning Range of 90nm

Optical filters capable of single control parameter-based wide tuning are implemented and studied. A prototype surface micromachined 1.3μm Si-based MOEMS (micro-opto-electro-mechanical-systems) tunable filter exhibits a continuous and large tuning range of 90 nm at 50 V tuning voltage. The filter can be integrated with Si-based photodetector in a low-cost component for coarse wavelength division multiplexing systems operating in the 1.3μm band.

The Incident Angle Dependence of Quantum Efficiency of GaAs Based RCE Photodetectors

The theoretical analysis and experimental measurement on the incident angle dependence of quantum efficiency of GaAs based resonant cavity enhanced (RCE) photodetector is presented. By changing the angle of incoming light, about 40 nm wavelength variation of peak quantum efficiency is obtained. The peak quantum efficiency and optical bandwidth at different mode corresponding to different angle incidence is characterized with different absorption dependence on wavelength. The convenient angle tuning of resonant mode will be helpful to relax the strict constraint of RCE photodetector to light source with narrow emission spectrum such applications in space optical detections and communications.

1.3 mu m GaInNAs/GaAs quantum well lasers and photodetectors

The growth of GalnNAs/GaAs quantum well (QW) has been investigated by solid-source molecular beam epitaxy (MBE). N was introduced by a dc-active plasma source. Highest N concentration of 2.6% in GaInNAs/GaAs QW was obtained, corresponding to the photoluminescence peak wavelength of 1.57 mum at 10K. The nitrogen incorporation behavior in MBE growth and the quality improvement of the QW have been studied in detail. 1.3 mum GaInNAs/GaAs SQW laser and MQW resonant-cavity enhanced photodetector have been achieved.

1.3 mu m GaInNAs/GaAs multiple-quantum-wells resonant-cavity-enhanced photodetectors

A GaInNAs/GaAs multiple quantum well (MQW) resonant-cavity enhanced (RCE) photodetector operating at 1.3 mum with the full-width at half-maximum of 5.5 nm was demonstrated. The GaInNAs RCE photodetector was grown by molecular-beam epitaxy using an ion-removed dc-plasma cell as nitrogen source. GaInNAs/GaAs MQW shows a strong exciton peak at room temperature that is very beneficial for applications in long-wavelength absorption devices. For a 100-mum diameter RCE photodetector, the dark current is 20 and 32 pA at biases of 0 and 6 V, respectively, and the breakdown voltage is -18 V. The measured 3-dB bandwidth is 308 MHz. The reasons resulting in the poor high speed property were analyzed. The tunable wavelength of 18 nm with the angle of incident light was observed.

Long-wavelength Si-based MQW photodetectors for application in optical fiber communication

Si-based SiGe/Si strained MQW long-wavelength photodetectors (PD) with cycle type (Ring Shape) waveguide (CWG) and resonant-cavity-enhanced (RCE) structure have been investigated for the first time for improving the quantum efficiency and response time. The results show that the responsivities are higher than that of conventional PD with a same Ge content reported previously. In addition, RCE-PD has an obvious narrow band response with FWHM less than 6nm.

Analysis for the angle dependence of GaAs based RCE photodetectors

The theoretical analysis and experimental measurement on the angle dependence of quantum efficiency of GaAs based resonant cavity enhanced (RCE) photodetector is presented. By changing the angle of incoming light, about 40mn wavelength variation of peak quantum efficiency has been experimentally obtained. The peak quantum efficiency and optical bandwidth at different mode corresponding to different angle incidence have been characterized with different absorption dependence on wavelength. The convenient angle tuning of resonant mode will be helpful to relax the strict constraint of RCE photodetector to light source with narrow emission spectrum while especially applied in space optical detections and communications.

VCSEL based optoelectronic multiple chip modules

We report on optoelectronic multiple chip modules, consisting of vertical cavity surface emitting laser(VCSEL), photodetector and 1.2 mum CMOS electronic circuit, The hybrid integrated components operate at a date rate of 155Mb/s, which could be used in optical interconnects for multiple computers.

Normal-incident SiGe/Si MQWs photodetectors operating at 1.3 mu m

A normal-incident SiGe/Si multiple quantum wells (MQWs) photodetector was reported. The structure and fabrication process of the photodetector were introduced. The photocurrent spectra measurement showed that the response spectra was expanded to 1.3 mu m wavelength. The quantum efficiency of the photodetector was 0.1% at 1.3 mu m and 20% at 0.95 mu m.

Asymmetric dark current in double barrier quantum well infrared photodetectors

Asymmetric dark current and photocurrent versus voltage characteristic in the Double Barrier Quantum Wells (DBQWs) photovoltaic infrared photodetector has been studied. A model based on asymmetric potential barriers was proposed. The asymmetric potential thick barrier, which due to the Si dopant segregation during growth makes a major contribution to the asymmetrical I-V characteristic, calculations based on our model agree well with experimental results. This work also confirms the potential use of this DBQWs for infrared photodetector with large responsivity and little dark current under negative bias.

Experimental study on tunable external cavity photodetectors

In this paper, an experiment on tunable resonant cavity enhanced (RCE) photodetector with external cavity is reported. It is the first time to realize a tunable RCE photodetector in China. A tuning range about 10 nm has been obtained and further extension is expected. Corresponding theoretical analysis and discussions are presented. (C) 2000 Elsevier Science B.V. All rights reserved.

Characteristics of circular waveguide photodetectors using SiGe/Si multiple quantum wells

We report on the fabrication of circular waveguide photodetectors with a response near 1.3 mu m wavelength using SiGe/Si multiple quantum wells. The quantum efficiency of the circular waveguide photodetector is improved when compared with that of the rib waveguide photodetector in the same wavelength at 1.3 mu m The frequency response of the photodetectors is simulated. The emciency-bandwidth product of the circular waveguide photodetectors is improved correspondingly. (C) 2000 Published by Elsevier Science B.V. All rights reserved.

Si-based optoelectronic devices and their attractive applications

The semiconductor photonics and optoelectronics which have a great significance in the development of advanced high technology of information systems will be discussed in this paper. The emphasis will be put on the recent research carried out in our laboratory in enhanced luminescence from low dimensional materials such as SiGe/Si and Er-doped Si-rich SiO2/Si and Er-doped SixNy/Si. A ring shape waveguide structure, used to promote the effective absorption coefficient in PIN photodetector for 1.3 mu m wavelength and a resonant cavity enhanced structure, used to improve the quantum efficiency and response in heterostructure photo-transistor (HPT), are also proposed in this paper.