{"id":2271,"date":"2026-07-08T03:27:19","date_gmt":"2026-07-08T03:27:19","guid":{"rendered":"https:\/\/photo-detector.com\/?p=2271"},"modified":"2026-07-08T03:27:26","modified_gmt":"2026-07-08T03:27:26","slug":"near-infrared-pin-photodiode-chip","status":"publish","type":"post","link":"https:\/\/photo-detector.com\/de\/near-infrared-pin-photodiode-chip\/","title":{"rendered":"Leitfaden zur Auswahl von Nahinfrarot-PIN-Fotodioden-Chips: Silizium vs. InGaAs f\u00fcr Galvosysteme"},"content":{"rendered":"\n

If you are a system architect or an optical design engineer, you have probably spent some sleepless nights staring at your Bill of Materials (BOM). You are staring at that one line item\u2014the photodetector\u2014and asking yourself if you really need to spend top dollar on Indium Gallium Arsenide (InGaAs), or if you can get away with cheap, reliable Silicon (Si).<\/p>\n\n\n\n

This design headache gets real when you are working in the 900 nm to 1100 nm wavelength band, especially for galvanometer-based scanning systems (Galvo systems). Whether it is a high-speed laser marking machine, a LiDAR setup, or a 3D metal printing system, your choice of a near infrared PIN photodiode chip is what keeps your beam positioning precise and your signal-to-noise ratio (SNR) clean.<\/p>\n\n\n\n

Let’s skip the textbook fluff and look at the actual physics, the real-world trade-offs, and how to choose the right near infrared PIN photodiode chip for your Galvo system without blowing your project budget.<\/p>\n\n\n\n

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Why the 900nm to 1100nm Band is an Engineering Battleground<\/h2>\n\n\n\n

Before we talk about the sensors themselves, we need to talk about why this specific wavelength range is so popular yet so difficult.<\/p>\n\n\n\n

The 900-1100 nm band is home to some of the most common lasers in the world. You have Nd:YAG and Ytterbium fiber lasers operating at 1064 nm. You have GaAs semiconductor lasers shooting out 905 nm and 940 nm beams. These wavelengths are awesome because they can pass through common optical fibers easily, they have decent atmospheric transmission, and they match the emission spectrum of many industrial processes.<\/p>\n\n\n\n

But here is the catch: this band lies right on the boundary of where Silicon stops working and InGaAs starts shining.<\/p>\n\n\n\n

For a silicon-based near infrared PIN photodiode chip, 1100 nm is the absolute end of the road. It represents the physical limit of the material’s bandgap. For an InGaAs-based near infrared PIN photodiode chip, this range is on the lower end of its sweet spot. This overlap means both materials are technically options, but they behave very differently in practice. If you choose the wrong near infrared PIN photodiode chip, you might end up with a system that is either way too expensive or plagued by terrible signal drift.<\/p>\n\n\n\n

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The Core Physics: Bandgaps and Responsivity (Without the Math Nightmare)<\/h2>\n\n\n\n

Let’s look at why these two materials behave the way they do. It all comes down to the bandgap energy of the semiconductor material inside your near infrared PIN photodiode chip.<\/p>\n\n\n\n

Silicon (Si) has a bandgap of about 1.12 electron-volts (eV) at room temperature.<\/p>\n\n\n\n

Indium Gallium Arsenide (InGaAs), specifically the type lattice-matched to Indium Phosphide, has a much smaller bandgap of around 0.75 eV.<\/p>\n\n\n\n

To generate an electrical signal, an incoming photon must have enough energy to kick an electron across this bandgap. The relationship between the cutoff wavelength (expressed as lambda_c) and the bandgap energy (Eg) can be written as:<\/p>\n\n\n\n

lambda_c = 1240 \/ Eg<\/p>\n\n\n\n

Where lambda_c is in nanometers (nm) and Eg is in eV.<\/p>\n\n\n\n

If we run the numbers for a silicon-based near infrared PIN photodiode chip, we get:<\/p>\n\n\n\n

lambda_c = 1240 \/ 1.12 = 1107 nm<\/p>\n\n\n\n

This is why a silicon near infrared PIN photodiode chip goes completely blind beyond 1100 nm. As you approach this limit, the photons simply do not have enough energy to excite the electrons. They pass right through the silicon crystal like it is window glass.<\/p>\n\n\n\n

For a standard InGaAs near infrared PIN photodiode chip, the calculation gives us:<\/p>\n\n\n\n

lambda_c = 1240 \/ 0.75 = 1653 nm<\/p>\n\n\n\n

This means an InGaAs near infrared PIN photodiode chip can easily absorb photons all the way up to 1650 nm, making the 900-1100 nm band a walk in the park for this material.<\/p>\n\n\n\n

Looking at how absorption changes across this band highlights the main differences:<\/p>\n\n\n\n

From 900 nm to 950 nm, Silicon maintains high quantum efficiency, making it highly competitive.<\/p>\n\n\n\n

From 950 nm to 1000 nm, Silicon’s absorption begins dropping steadily, requiring larger active areas or better amplification.<\/p>\n\n\n\n

At 1064 nm, Silicon’s performance is poor, making it highly transparent, whereas InGaAs maintains high, stable quantum efficiency across the entire 900 nm to 1100 nm range.<\/p>\n\n\n\n

Quantum Efficiency and Responsivity<\/h3>\n\n\n\n

Quantum efficiency (QE) is the percentage of incident photons that successfully create electron-hole pairs inside your near infrared PIN photodiode chip. Responsivity (R) is the actual current output you get per watt of incident light, measured in Amps per Watt (A\/W).<\/p>\n\n\n\n

The relationship between the two is simple:<\/p>\n\n\n\n

R = (QE * q * lambda) \/ (h * c)<\/p>\n\n\n\n

Or, in simpler terms:<\/p>\n\n\n\n

R is approximately equal to (QE * lambda) \/ 1240<\/p>\n\n\n\n

At 940 nm, a high-quality silicon near infrared PIN photodiode chip like the PDC-C2928-NIR-B 940nm PIN photodiode chip<\/a><\/strong> can achieve a QE of over 70%, resulting in a responsivity of about 0.55 A\/W.<\/p>\n\n\n\n

But watch what happens when we move to 1064 nm. The QE of standard silicon drops off a cliff, often falling below 15%. This leaves you with a tiny responsivity of around 0.12 A\/W.<\/p>\n\n\n\n

In contrast, an InGaAs near infrared PIN photodiode chip maintains a QE of nearly 90% across the entire 900-1100 nm range. At 1064 nm, its responsivity sits comfortably at 0.78 A\/W. That is a massive difference in signal strength.<\/p>\n\n\n\n

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