By using High-Voltage Ion Implantation, PREMA can offer several types of photodiodes with different spectral sensitivities. Unless stated otherwise, photodiodes are type I.
Because all in semiconductor industry common fabrication techniques are available, photodiodes can be closely packed next to each other. (Arrays of photodiodes)
For applications using higher frequencies, a special type of photodiodes with reduced capacitances (< 25 pF/mm²) is available. Very low dark current with less than 100 pA at reverse voltages of 10 V can be achieved.
Wireless Retina Implant Electrostimulates Ganglion Cells
Wafers with PREMA photodiodes consisting of pn-junctions close to the upper surface have been back-grinded to 20 µm, 35 µm, 60 µm and 100 µm. The spectral sensitivity of singulated photodiodes has been measured with back-side illumination. The spectral sensitivity is increased up to 0,18 A/W by a metal cap above the photodiodes. Here, photons that have not been absorbed are reflected. The retina implant consists of thinned photodiodes embedded in a foil substrate. While the light enters the photodiode at the back-side, the contact pads at the front-side can be utilized to electro-stimulate the ganglion cells.
PREMA IC PR5001
With minimal size, the PR5001 is a dual photo diode with a wideband spectral sensitivity (450-950 nm) with peak at 800 nm. An active area of two times 0.75 mm x 1.2 mm is packaged in a small transparent DFN package with a size of only 1.8 mm x 2.9 mm. The silicon photo diodes have separate cathodes and a common anode.
PREMA IC PR5001-IR
An IR transparent but black ODFN package enables a spectral sensitivity of the silicon photodiodes between 700 and 1100 nm. Without any significant sensitivity for visible light, therefore PR5001-IR is suitable to detect near infrared radiation.
PREMA IC PR5010
PR5010 is a double silicon photodiode with two symmetrical anodes and a common cathode, sensitive for visible light. The cathode forms an additional photodiode to the substrate that is sensitive for infrared light.
Key features are the low dark current combined with a high sensitivity and an antireflective coating on the die. PR5010 is available in an optical DFN package with a very small formfactor.
PREMA IC PR5020/21
PR5020 and PR50221 are triple silicon photodiodes with three separate cathodes and one common anode. Therefore, the three segments allow to resolve two transitions. With a wider and thinner photodiode in the center of the die, the PR5020 and the PR5021 are symmetrically designed. Both types offer a low dark current combined with a high sensitivity. The dies are moulded into a small plastic leadless optical DFN package.
PREMA IC PR5030
PR5030 is a dual silicon photodiode with two separate cathodes and one common anode. Each photodiode has a triangular shape to form an interface along the diagonal of the die. Therefore, the two segments allow to resolve a position of a slit or an edge above. Both types offer a low dark current combined with a high sensitivity. The dies are moulded into a small plastic leadless optical DFN package.
PREMA IC PR5040
PR5040 is a single silicon photodiode with rectangular shape having the same outer dimensions as the seqmented types PR5001-PR5030. The photodiode has a low dark current combined with a high sensitivity. The dies are moulded into a small plastic leadless optical DFN package.