Mesa-isolated InGaAs photodetectors with low dark current

Bidenko

IEEE Electron Device Lett.

et al. 2021

A vertical bi-stable resistor (biristor) composed of In 0.53 Ga 0.47 As was demonstrated for sub-1 V operation. An inherent small bandgap and a scaled base length of 150 nm led to the remarkable reduction in latchup voltage compared to Si(Ge)-based conventional biristors. The epitaxially grown n-p-n structure allowed an abrupt p-n junction, which was also very important to reduce the latchup voltage. Furthermore, the physical mechanism of carrier transport in the InGaAs biristor was explored with TCAD simulations.Index Terms-3-D integration, abrupt junction artificial neural network, epitaxial growth, impact ionization, InGaAs, vertical biristor. I. INTRODUCTIONA LTHOUGH the capacitor-less one-transistor dynamic random-access memory (1T-DRAM) has shown great potential of being able to replace conventional DRAM with a higher packing density beyond 4F 2 , its three-terminal structure suffers from inherent gate reliability issues, such as hot carrier injection. [1], [2] To mitigate these issues, the bistable-resistor abbreviated as "biristor", has been developed. A biristor is an open-based two-channel bipolar junction transistor with a collector-base-emitter structure with a doping profile of either n + -p-n + or p + -n-p + . Biristors have shown promising characteristics with enhanced endurance and reliability for post-DRAM technology applications thanks to their gate-less operation. [3]-[6] Compared to 1T-DRAM, another attractive aspect of biristors is their potential for further cell size reduction thanks to their gate-less structure. In principle, when a biristor is formed vertically, the packing density can be reduced to be as small

Section: Resultsmentioning

confidence: 99%

Vertical InGaAs Biristor for Sub-1 V Operation

Bidenko

IEEE Electron Device Lett.

et al. 2021

Turk J Elec Eng & Comp Sci

“…Next, dark and photocurrent calculations including sensitivity analysis with respect to different delta-doping concentrations and various barrier heights adjusted by Al-Ga mole fraction ratio are discussed for the proposed nBn detector. In the simulations, optical calculations were done at 1.55 µ m under 0.01 W/cm 2 optical power per unit area in the normal direction to the epitaxial structure from the substrate side (back illuminated) while the absorption coefficient of In 0.53 Ga 0.47 As at 1.55 µ m was considered as 7000 cm -1 [13,33,43]. Figure 6a shows the dark and photocurrent densities versus delta-doping layer concentrations and Figure 6b illustrates the adjustable valence and conduction band offsets with delta-doping layer doping concentrations.…”

Section: Resultsmentioning

confidence: 99%

“…Regarding the InGaAs based SWIR detectors, both pn with barrier and nBn type detectors have been shown to provide successful results [13,33,34], and here a novel nBn detector with lower dark current is numerically proposed. The barrier layer (together with the delta-doped layers similar to all InGaAs designs [33]) is designed with an InAlGaAs quaternary compound that linearly grades from low band gap to high band gap by changing the ratio of the Al-Ga mole fraction so that the lattice-mismatch is minimized.…”

Section: Introductionmentioning

confidence: 99%

“…As the benefit here comes from quaternary compounds (more difficult material growth), the idea here is to present a novel structure that could be useful in the case that modern sophisticated material growth capabilities are available.Reverse biased band diagram characteristics for the structures shown inFigure 4are presented inFigure 5, whereFigure 5ashows the pn junction (N d = 5 × 10 16 cm -3 , N a = 5 × 10 16 cm -3 ) and Figures 5b and 5c illustrate the nBn structures discussed above. The nBn designs both include an InGaAs lattice-matched absorber (N d = 5 × 10 16 cm -3 ), contact layer (N d = 6 × 10 16 cm -3 ), high bandgap barrier (undoped), and linearly compositional graded (undoped) and dipole delta-doped (N d = N a = 1.1 × 10 18 cm -3 ) layers wherethe valence band offset is removed with the help of delta-dopings[13,33,34,40,41]. Doping levels are chosen considering the case where absorber doping up to low 10 17 cm -3 levels has been shown to lower the dark current[42].…”

mentioning

confidence: 99%

See 1 more Smart Citation

InGaAs nBn SWIR detector design with lattice-matched InAlGaAs barrier

Uzgur¹,

Kocaman²

2019

Dark current optimization with band gap engineering has been numerically studied for InGaAs nBn type infrared photodetectors. Undoped InAlGaAs grading layers are utilized in constructing the barrier and dipole deltadoped layers are placed in both sides of the graded layers for eliminating valence band offset. As a result, the high band gap barrier layer blocks the majority carriers and allows minority carrier flow while minimizing various dark current components, as expected from an nBn detector. Substantial improvement has been shown in the dark current level without compromising any photoresponse compared to the conventional pn junction and recently proposed all InGaAs nBn type photodetectors.

Physica Status Solidi (a)

“…The bias applied for these measurements was −1 V. Both dark current levels are significantly higher than that typically reported for photodiodes. [ 25–27 ] Fabrication was not optimized, and not specifically crafted for photodiode applications. However, dark current measurements do reveal device performance aspects such as leakage current and activation energy.…”

Section: Lasing Characteristicsmentioning

confidence: 99%

Lasing Characteristics and Reliability of 1550 nm Laser Diodes Monolithically Grown on Silicon

Shi

Pinna

Zhao

et al. 2020

Room‐temperature continuous wave (RT‐CW) electrically pumped 1550 nm indium phosphide (InP)‐based laser diodes are realized on complementary metal‐oxide‐semiconductor (CMOS) compatible silicon (Si) substrates by direct heteroepitaxy. Dynamic properties are investigated by gain switching and small signal modulation measurements. A maximum 3 dB bandwidth of 5.3 GHz is demonstrated, along with a narrow optical pulse with a width of 1.5 ns. The dark current density of 490 mA cm−2 at −1 V bias is an order of magnitude higher than identical devices grown and fabricated on native InP substrates. Also, reliability measurements and failure analysis are carried out for the lasers on Si. The lasers operate stably over 200 hours (h) at 10 °C under CW operation without apparent change in threshold or output power. In sharp contrast, a rapid failure occurs at 60 °C under pulsed operation following 5.6 h of aging. To further improve device characteristics for lasers on Si, the dislocation density of the InP template is reduced by introducing a 2 μm‐thick compositionally graded In0.4Ga0.6 As buffer. The resulting surface defect density is as low as 4.5 × 107 cm−2, which is expected to improve the performance and reliability of long wavelength lasers grown directly on Si.