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519 Articles

Pulsed Deposition Points A Different Path To DIY Semiconductors

February 19, 2025 by 1 Comment

While not impossible, replicating the machines and processes of a modern semiconductor fab is a pretty steep climb for the home gamer. Sure, we’ve seen it done, but nanoscale photolithography is a demanding process that discourages the DIYer at every turn. So if you want to make semiconductors at home, it might be best to change the rules a little and give something like this pulsed laser deposition prototyping apparatus a try.

Rather than building up a semiconductor by depositing layers of material onto a silicon substrate and selectively etching features into them with photolithography, [Sebastián Elgueta]’s chips will be made by adding materials in their final shape, with no etching required. The heart of the process is a multi-material pulsed laser deposition chamber, which uses an Nd:YAG laser to ablate one of six materials held on a rotating turret, creating a plasma that can be deposited onto a silicon substrate. Layers can either be a single material or, with the turret rapidly switched between different targets, a mix of multiple materials. The chamber is also equipped with valves for admitting different gases, such as oxygen when insulating layers of metal oxides need to be deposited. To create features, a pattern etched into a continuous web of aluminum foil by a second laser is used as a mask. When a new mask is needed, a fresh area of the foil is rolled into position over the substrate; this keeps the patterns in perfect alignment.

We’ve noticed regular updates on this project, so it’s under active development. [Sebastián]’s most recent improvements to the setup have involved adding electronics inside the chamber, including a resistive heater to warm the substrate before deposition and a quartz crystal microbalance to measure the amount of material being deposited. We’re eager to see what else he comes up with, especially when those first chips roll off the line. Until then, we’ll just have to look back at some of [Sam Zeloof]’s DIY semiconductors.

Growing A Gallium-Arsenide Laser Directly On Silicon

February 7, 2025 by 10 Comments

As great as silicon is for semiconductor applications, it has one weakness in that using it for lasers isn’t very practical. Never say never though, as it turns out that you can now grow lasers directly on the silicon material. The most optimal material for solid-state lasers in photonics is gallium-arsenide (GaAs), but due to the misalignment of the crystal lattice between the compound (group III-V) semiconductor and silicon (IV) generally separate dies would be produced and (very carefully) aligned or grafted onto the silicon die.

Naturally, it’s far easier and cheaper if a GaAs laser can be grown directly on the silicon die, which is what researchers from IMEC now have done (preprint). Using standard processes and materials, GaAs lasers were grown on industry-standard 300 mm silicon wafers. The trick was to accept the lattice mismatch and instead focus on confining the resulting flaws through a layer of silicon dioxide on top of the wafer. In this layer trenches are created (see top image), which means that when the GaAs is deposited it only contacts the Si inside these grooves, thus limiting the effect of the mismatch and confining it to within these trenches.

There are still a few issues to resolve before this technique can be prepared for mass-production, of course. The produced lasers work at 1,020 nm, which is a shorter wavelength than typically used, and there are still some durability issues due to the manufacturing process that have to be addressed.

Dress Up Your 3D Prints With Toner-Transfer Labels

January 2, 2025 by 25 Comments

We’ve always found the various methods for adding text and graphics to 3D prints somewhat underwhelming. Embossed or debossed characters are fuzzy, at best, and multi-color printers always seem to bleed one color into the next. Still, the need for labels and logos is common enough that it’s worth exploring other methods, such as this easy toner transfer trick.

Home PCB makers will probably find the method [Squalius] describes in the video below very familiar, and with good reason. We’ve seen toner transfer used to mask PCBs before etching, and the basic process here is very similar. It starts with printing the desired graphics on regular paper using a laser printer; don’t forget to mirror the print. The printed surface is scuffed up a bit, carefully cleaned, and coated with a thick layer of liquid acrylic medium, of the kind used in paint pouring. The mirrored print is carefully laid on the acrylic, toner-side down, and more medium is brushed on the back of the paper. After the print dries, the paper is removed with a little water and some gentle friction, leaving the toner behind. A coat of polyurethane protects the artwork reasonably well.

[Squalius] has tested the method with PLA and PETG and reports good results. The text is clear and sharp, and even fine text and dithered graphics look pretty good. Durability could be better, and [Squalius] is looking for alternative products that might work better for high-wear applications. It looks like it works best on lightly textured surfaces, too, as opposed to surfaces with layer lines. We’d love to see if color laser prints work, too; [Squalius] says that’s in the works, and we’ve seen examples before that are reason for optimism.

Continue reading “Dress Up Your 3D Prints With Toner-Transfer Labels” →

Taking “Movies” Of Light In Flight

December 25, 2024 by 10 Comments

This one isn’t clickbait, but it is cheating. [Brian Haidet], the guy behind Alpha Phoenix, has managed to assemble movie footage of a laser beam crossing his garage, using a rig he put together for just a few hundred dollars. How, you ask? Well, for the long version, you’re going to want to watch the video, also embedded below. But we’ll give you the short version here.

Light travels about a foot in a nanosecond. What have you got that measures signals on a nanosecond scale pretty reliably? Of course, it’s your oscilloscope. The rest of [Brian]’s setup includes a laser that can pull off nanosecond pulses, a sensor with a nanosecond-ish rise time, and optics that collect the light over a very small field of view.

He then scans the effective “pinhole” across his garage, emitting a laser pulse and recording the brightness over time on the oscilloscope for each position. Repeating this many thousands of times and putting them all together relative to the beginning of each laser pulse results in a composite movie with the brightness at each location resolved accurately enough to watch the light beam fly. Or to watch different time-slices of thousands of beams fly, but as long as they’re all the same, there’s no real difference.

Of course, this isn’t simple. The laser driver needs to push many amps to get a fast enough rise time, and the only sensor that’s fast enough to not smear the signal is a photomultiplier tube. But persistence pays off, and the results are pretty incredible for something that you could actually do in your garage.

Photomultiplier tubes are pretty damn cool, and can not only detect very short light events, but also very weak ones, down to a single photon. Indeed, they’re cool enough that if you get yourself a few hundred thousand of them and put them in a dark place, you’re on your way to a neutrino detector.  Continue reading “Taking “Movies” Of Light In Flight” →

Automated Rig Grows Big, Beautiful Crystals Fast

December 12, 2024 by 8 Comments

We haven’t seen [Les Wright] in a while, and with the release of his new video, we know why — he’s been busy growing crystals.

Now, that might seem confusing to anyone who has done the classic “Crystal Garden” trick with table salt and laundry bluing, or tried to get a bit of rock candy out of a supersaturated sugar solution. Sure, growing crystals takes time, but it’s not exactly hard work. But [Les] isn’t in the market for any old crystals. Rather, he needs super-sized, optically clear crystals of potassium dihydrogen phosphate, or KDP, which are useful as frequency doublers for lasers. [Les] has detailed his need for KDP crystals before and even grown some nice ones, but he wanted to step up his game and grow some real whoppers.

And boy, did he ever. Fair warning; the video below is long and has a lot of detail on crystal-growing theory, but it’s well worth it for anyone taking the plunge. [Les] ended up building an automated crystal lab, housing it in an old server enclosure for temperature and dust control. The crystals are grown on a custom-built armature that slowly rotates in a supersaturated solution of KDP which is carefully transitioned through a specific temperature profile under Arduino control. As a bonus, he programmed the rig to take photographs of the growing crystals at intervals; the resulting time-lapse sequences are as gorgeous as the crystals, one of which grew to 40 grams in only a week.

We’re keen to see how [Les] puts these crystals to work, and to learn exactly what a “Pockels Cell” is and why you’d want one. In the meantime, if you’re interested in how the crystals that make the whole world work are made, check out our deep dive into silicon.

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Custom built RGB laser firing beam

Lasers, Galvos, Action: A Quest For Laser Mastery

November 22, 2024 by 1 Comment

If you’re into hacking hardware and bending light to your will, [Shoaib Mustafa]’s latest project is bound to spike your curiosity. Combining lasers to project multi-colored beams onto a screen is ambitious enough, but doing it with a galvanomirror, STM32 microcontroller, and mostly scratch-built components? That’s next-level tinkering. This project isn’t just a feast for the eyes—it’s a adventure of control algorithms, hardware hacks, and the occasional ‘oops, that didn’t work.’ You can follow [Shoaib]’s build log and join the journey here.

The nitty-gritty is where it gets fascinating. Shoaib digs into STM32 Timers, explaining how modes like Timer, Counter, and PWM are leveraged for precise control. From adjusting laser intensity to syncing galvos for projection, every component is tuned for maximum flexibility. Need lasers aligned? Enter spectrometry and optical diffusers for precision wavelength management. Want real-time tweaks? A Python-controlled GUI handles the instruments while keeping the setup minimalist. This isn’t just a DIY build—it’s a work of art in problem-solving, with successes like a working simulation and implemented algorithms along the way.

If laser projection or STM32 wizardry excites you, this build will inspire. We featured a similar project by [Ben] back in September, and if you dig deep into our archives, you can eat your heart out on decades of laser projector projects. Explore Shoaib’s complete log on Hackaday.io. It is—literally—hacking at its most brilliant.

The Laser Shadow Knows

November 18, 2024 by 31 Comments

Normally, you think of things casting a shadow as being opaque. However, new research shows that under certain conditions, a laser beam can cast a shadow. This may sound like nothing more than a novelty, but it may have applications in using one laser beam to control another. If you want more details, you can read the actual paper online.

Typically, light passes through light without having an effect. But using a ruby crystal and specific laser wavelengths. In particular, a green laser has a non-linear response in the crystal that causes a shadow in  a blue laser passing through the same crystal.

Continue reading “The Laser Shadow Knows” →