Jin-Kwon Park

Low resistivity lateral P–I–N junction formed by Ni–InGaAsP alloy for carrier injection InGaAsP photonic devices

In this study, we investigate low-resistivity InGaAsP lateral P–I–N junctions using Ni–InGaAsP alloy in conjunction with Zn diffusion. It is found that Ni–InGaAsP alloy is formed via a direct reaction between Ni and InGaAsP after annealing at more than 300 °C. The Ni–InGaAsP preserves the initial Schottky junction properties between Ni and InGaAsP, and thus exhibits an ohmic contact for n-InGaAsP and a Schottky contact for p-InGaAsP. Hence, the Ni–InGaAsP alloy can be used instead of the Si ion implantation process to form the P–I–N junction. The Ni–InGaAsP alloy exhibits significantly lower contact resistance and sheet resistance than Si implanted n+-InGaAsP. The InGaAsP lateral P–I–N junction formed with the Ni–InGaAsP alloy and Zn diffusion shows approximately 10 times lower access resistance than the n+-InGaAsP junction. Thus, we successfully achieve large on-current in the lateral P–I–N junction with the Ni–InGaAsP alloy. The fabrication procedure of the lateral P–I–N junction using the Ni–InGaAsP alloy is promising for carrier-injection photonic devices on the III–V CMOS photonics platform.

Heterogeneous CMOS Photonics Based on SiGe/Ge and III–V Semiconductors Integrated on Si Platform

The heterogeneous integration of SiGe, Ge, and III–V semiconductors on Si provides many opportunities to develop high-performance photonic integrated circuits through complementary metal oxide semiconductor (CMOS) processes. We found that strained SiGe possesses greater free-carrier effects than Si, contributing to the improved modulation efficiency of Si-based optical modulators. In addition to low-dark-current Ge photodetectors (PDs) with GeO 2 passivation, we investigated Ge CMOS photonics platform for midinfrared wavelengths. We demonstrated Ge passive waveguides and carrier-injection variable optical attenuators (VOAs) on a Ge-on-insulator wafer. We also investigated III–V CMOS photonics platform on a III–V-on-insulator (III–V-OI) wafer. The strong optical confinement in the III–V-OI structure enabled the realization of ultrasmall III–V passive waveguides similarly to those in Si photonics. Carrier-injection InGaAsP optical switches and VOAs as well as InGaAs waveguide PDs were also demonstrated on III–V-OI wafers. We discuss the opportunities and challenges of heterogeneous CMOS photonics technologies to develop high-performance electronic–photonic integrated circuits for near-infrared and midinfrared applications.

CMOS photonics technologies based on heterogeneous integration of SiGe/Ge and III-V on Si

In this paper, we present heterogeneous integration of SiGe/Ge and III-V semiconductors on Si for electronic-photonic integrated circuits through CMOS photonics technologies. The introduction of high-mobility channel materials, which is promising for achieving high-performance MOSFETs, are also beneficial to photonics for off-chip/on-chip optical interconnection and bio/medical sensors. As for SiGe CMOS photonics, strained SiGe is shown to enhance modulation efficiency for optical modulators. We demonstrated that the plasma dispersion effect is enhanced by strain application to SiGe owing to a decrease in the effective hole mass. As for Ge CMOS photonics, Ge-based photonic-wire waveguides are demonstrated for Mid-IR applications by using photonic Ge-on-Insulator wafers for the first time. As for III-V CMOS photonics, we developed high-quality photonic III-V on Insulator wafers by using direct wafer bonding. InGaAsP photonic-wire devices including optical switches and InGaAs photodetectors are demonstrated. We have also successfully demonstrated wafer-size-scalable III-V-OI wafers by using a III-V epi on Si wafer.

Development of high-performance fully depleted silicon-on-insulator based extended-gate field-effect transistor using the parasitic bipolar junction transistor effect

Latch based extended-gate field effect transistors (EGFETs) with a high on/off current ratio were realized on the fully depleted silicon-on-insulator (SOI) substrate. A large on/off current ratio characteristic as high as 104 with a very steep subthreshold swing close to 0 mV/dec was achieved by using the latch characteristic of the SOI substrate, which means it is highly sensitive to the small surface potential variation of biomaterials. Therefore, latch based EGFET sensors are a very promising candidate to break through the poor signal to the noise ratio exposed on conventional biosensors.

Heterogeneous integration of SiGe/Ge and III-V for Si photonics

The heterogeneous integration of SiGe/Ge and III-V semiconductors gives us an opportunity to enhance functionalities of Si photonics platform through their superior material properties which lack in Si. In this paper we discuss what SiGe/Ge and III-V can bring to Si photonics. We have predicted that the light effective hole mass in strained SiGe results in the enhanced the free-carrier effects such as the plasma dispersion effect and free-carrier absorption. We observed significantly larger free-carrier absorption in the SiGe optical modulator than in the control Si device. By fabricating asymmetric Mach-Zehnder interferometer (MZI) SiGe optical modulators, the enhancement of the plasma dispersion effect in strained SiGe has been successfully demonstrated. Mid-infrared integrated photonics based on Ge waveguides on Si have also been investigated. Since Ge is transparent to the entire mid-infrared range, Ge photonic integrated circuits on the Ge-on-Insulator (GeOI) wafer are quite attractive. We have successfully fabricated the GeOI wafer with 2-μm-thick buried oxide (BOX) layer by wafer bonding. The passive waveguide components based on Ge strip waveguides have been demonstrated on the GeOI. We have also demonstrated carrier-injection Ge variable optical attenuators. We have proposed and investigate the III-V CMOS photonics platform by using the III-V on Insulator (IIIV- OI) on a Si wafer. The strong optical confinement in the III-V-OI enables us to achieve high-performance photonic devices. We have successfully demonstrated InGaAsP MZI optical switch with the low on-state crosstalk on the III-V-OI. Ultra-low dark current waveguide InGaAs PDs integrated with an InP grating coupler are also achieved.