ABSTRACT
3D integration of III-V semiconductors with Si CMOS is highly attractive since it allows combining new functions such as photonic and analog devices with digital signal processing circuitry. Thus far, most 3D integration approaches have used epitaxial growth on Si, layer transfer by wafer bonding, or die-to-die packaging. Here we present low-temperature integration of InAs on W using Si3N4 template assisted selective area metal-organic vapor-phase epitaxy (MOVPE). Despite growth nucleation on polycrystalline W, we can obtain a high yield of single-crystalline InAs nanowires, as observed by transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD). The nanowires exhibit a mobility of 690 cm2/(V s), a low-resistive, Ohmic electrical contact to the W film, and a resistivity which increases with diameter attributed to increased grain boundary scattering. These results demonstrate the feasibility for single-crystalline III-V back-end-of-line integration with a low thermal budget compatible with Si CMOS.
ABSTRACT
Monolithic integration of InSb on Si could be a key enabler for future electronic and optoelectronic applications. In this work, we report the fabrication of InSb metal-semiconductor-metal photodetectors directly on Si using a CMOS-compatible process known as rapid melt growth. Fourier transform spectroscopy demonstrates a spectrally resolved photocurrent peak from a single crystalline InSb nanostructure with dimensions of 500 nm × 1.1 µm × 120 nm. Time-dependent optical characterization of a device under 1550 nm illumination indicated a stable photoresponse with responsivity of 0.50 A W-1 at 16 nW illumination, with a time constant in the range of milliseconds. Electron backscatter diffraction spectroscopy revealed that the single crystalline InSb nanostructures contain occasional twin defects and crystal lattice twist around the growth axis, in addition to residual strain, possibly causing the observation of a low-energy tail in the detector response extending the photosensitivity out to 10 µm wavelengths (0.12 eV) at 77 K.
ABSTRACT
Ferroelectric memories based on hafnium oxide are an attractive alternative to conventional memory technologies due to their scalability and energy efficiency. However, there are still many open questions regarding the optimal material stack and processing conditions for reliable device performance. Here, we report on the impact of the sputtering process conditions of the commonly used TiN top electrode on the ferroelectric properties of Hf1-xZrxO2. By manipulating the deposition pressure and chemistry, we control the preferential orientation of the TiN grains between (111) and (002). We observe that (111) textured TiN is superior to (002) texturing for achieving high remanent polarization (Pr). Furthermore, we find that additional nitrogen supply during TiN deposition leads to >5× greater endurance, possibly by limiting the scavenging of oxygen from the Hf1-xZrxO2 film. These results help explain the large Pr variation reported in the literature for Hf1-xZrxO2/TiN and highlights the necessity of tuning the top electrode of the ferroelectric stack for successful device implementation.
ABSTRACT
Monolithic integration of III-V semiconductors with Silicon technology has instigated a wide range of new possibilities in the semiconductor industry, such as combination of digital circuits with optical sensing and high-frequency communication. A promising CMOS compatible integration process is rapid melt growth (RMG) that can yield high quality single crystalline material at low cost. This paper represents the study on ultra-thin InSb-on-insulator microstructures integrated on a Si platform by a RMG-like process. We utilize flash lamp annealing (FLA) to melt and recrystallize the InSb material for an ultra-short duration (milliseconds), to reduce the thermal budget necessary for integration with Si technology. We compare the result from FLA to regular rapid thermal annealing (seconds). Recrystallized InSb was characterized using electron back scatter diffraction which indicate a transition from nanocrystalline structure to a crystal structure with grain sizes exceeding 1 µm after the process. We further see a 100× improvement in electrical resistivity by FLA annealed sample when compared to the as-deposited InSb with an average Hall mobility of 3100 cm2 V-1 s-1 making this a promising step towards realizing monolithic mid-infrared detectors and quantum devices based on InSb.
