The polarization of traditional photonic crystal（PC） vertical cavity surface emitting laser（VCSEL） is uncontrollable,resulting in the bit error increasing easily.Elliptical hole photonic crystal can control the transverse mode and polarization of VCSEL efficiently.We analyze the far field divergence angle,and birefringence of elliptical hole PC VCSEL.When the ratio of minor axis to major axis b/a = 0.7,the PC VCSEL can obtain single mode and polarization.According to the simulation results,we fabricate the device successfully.The output power is 1.7 mW,the far field divergence angle is less than 10°,and the side mode suppression ratio is over 30 dB.The output power in the Y direction is 20 times that in the X direction.
A three-terminal silicon-based light emitting device is proposed and fabricated in standard 0.35 μm complementary metal-oxide-semiconductor technology. This device is capable of versatile working modes： it can emit visible to near infra-red （NIR） light （the spectrum ranges from 500 nm to 1000 nm） in reverse bias avalanche breakdown mode with working voltage between 8.35 V-12 V and emit NIR light （the spectrum ranges from 900 nm to 1300 nm） in the forward injection mode with working voltage below 2 V. An apparent modulation effect on the light intensity from the polysilicon gate is observed in the forward injection mode. Furthermore, when the gate oxide is broken down, NIR light is emitted from the polysilicon/oxide/silicon structure. Optoelectronic characteristics of the device working in different modes are measured and compared. The mechanisms behind these different emissions are explored.
在标准互补金属氧化物半导体(complementary metal oxide semiconductor,CMOS)工艺下设计了1种单片集成金属-半导体-金属(metal-semiconductor-metal,MSM)光电探测器的光接收机.带有源反馈和负米勒反馈电容的跨阻前置放大器用来提高光接收机的带宽.由于MSM光电探测器具有较高的响应度,所以光接收机的灵敏度得到改善.由于MSM光电探测器的寄生电容较小,在特许半导体0.35μm工艺下实现了带宽为1.7GHz的光接收机.测试结果表明,在-15dBm的光功率和误码率为10-9的条件下,光接收机的数据传输速率达到了2Gb/s.在3.3V电压下,芯片的功耗为94mW.
A novel superimposed photodetector （PD） is put forward. The photodetector can obtain a couple Of differential photocur- rent signals from one input optical signal. The light injection efficiency and the vertical work distance of this new.photode- tector are much higher than those of the others. The superimposed photodetctor is designed based on the standard 0.18 p.m CMOS process. The responsivity, bandwidth and transient response of the photodetector are simulated by a commercial simulation software of ATLAS. The responsivities of two obtained photocurrent signals are 0.035 A/W and 0.034 A/W, while the bandwidths are 3.8 GHz and 5.2 GHz, respectively. A full differential optical receiver which uses the superim- posed photodetector as input is simulated. The frequency response and 4 Gbit/s eye diagram of the optical receiver are also obtained. The results show that the two output signals can be used as the differential signal.
A novel negative-resistance transistor (NRT) with a Lambda shaped I-V characteristic is demonstrated in the 0.5 μm standard CMOS process. To save on the number of component devices, this device does not use standard device models provided by CMOS processes, but changes a MOSFET and a BJT into a single device by fabricating them in the same n-well, with a p-type base layer as the MOSFET's substrate. The NRT has a low valley current of -6.82 nA and a very high peak-to-valley current ratio of 3591. The peak current of the device is -24.49 μA which is low enough to reduce the power consumption of the deivce, and the average value of its negative resistance is about 32 kΩ. Unlike most negative-resistance devices which have been fabricated on compound semiconductor substrates in recent years, this novel NRT is based on a silicon substrate, compatible with mainstream CMOS technology. Our NRT dramatically reduces the number of devices, minimizing the area of the chip, has a low power consumption and thus a further reduction in cost.
