Back-illuminated AlGaN heterostructure solar-blind avalanche photodiodes with one-dimensional photonic crystal filter

Abstract

AlGaN heterostructure solar-blind avalanche photodiodes (APDs) were fabricated on a double-polished AlN/sapphire template based on a separate absorption and multiplication (SAM) back-illuminated configuration. By employing AlGaN heterostructures with different Al compositions across the entire device, the SAM APD achieved an avalanche gain of over 1×105 at an operated reverse bias of 92 V and a low dark current of 0.5 nA at the onset point of breakdown. These excellent performances were attributed to the acceleration of holes by the polarization electric field with the same direction as the reverse bias and higher impact ionization coefficient of the low-Al-content Al0.2Ga0.8N in the multiplication region. However, the Al0.2Ga0.8N layer produced a photocurrent response in the out of the solar-blind band. To retain the solar-blind detecting characteristic, a periodic Si3N4/SiO2 photonic crystal was deposited on the back of the AlN/sapphire template as an optical filter. This significantly improved the solar-blind characteristic of the device.

Progress on photovoltaic AlGaN photodiodes for solar-blind ultraviolet photodetection

“…The AlGaN heterostructure is receiving increasing attention for its excellent properties on APD SBPDs [39,105,132] . Shao et al [104] reported a type of AlGaN-heterostructure APD SBPD with the multiplication region composed of high/ low-Al-content AlGaN layers.…”

Investigation of Ga2O3/diamond heterostructure solar-blind avalanche photodiode via TCAD simulation

“…Currently, ultraviolet avalanche photodiodes (APDs) based on SiC, GaN/AlGaN and GaN/SiC have been successfully fab-ricated and can reach a gain as high as 1 × 10 5 at room temperature. [10][11][12] However, since the bandgaps of SiC and GaN are barely 3.23 eV and 3.4 eV at room temperature, respectively, they have high responsivity in the 300 nm-365 nm band, which is beyond solar-blind detection range (< 280 nm). Hence, APDs with ultrawide-bandgap semiconductors are currently being investigated.…”

Unipolar carrier multiplication high-gain and low-noise AlGaN ultraviolet avalanche photodiode with periodically stacked structure

“…Subsequently, the separate absorption and multiplication structure has been utilized to generate electron-hole pairs in the absorption region. Based on the electric field regulation through interlayer, the single kind of carrier enters the multiplication region to initiate impact ionization [18][19][20]. To a certain extent, the single carrier trigger multiplication effect is realized.…”