The tech sector held up relatively well in the COVID-19 spring of 2020. The tech-heavy NASDAQ Composite Index is up 8% year to date while the broader-market S&P 500 is trading down by 3%. But there are still plenty of deep-discount tech stocks on the table, and some of those finds involve rock-solid companies with great long-term business plans.

Here are three tech stocks that really shouldn't sit in Wall Street's bargain bin today, but that's exactly where you'll find them.

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Micron Technology

Memory-chip giant Micron Technology (NASDAQ:MU) has fallen 9% in 2020, and the stock is trading 20% below February's 52-week highs. You can pick up Micron shares for the ultralow valuation of 10 times forward earnings right now.

The coronavirus pandemic slammed the brakes on short-term demand for many of Micron's most important target markets, including smartphones and cars, which explains why the stock is so cheap right now. But the health crisis also softened that blow by driving strong demand for home office equipment such as desktop and laptop computers, better home networking gear, and handy tablet computers -- all of which require plenty of DRAM and NAND memory chips. Cloud computing is another red-hot sector that leans heavily on DRAM and NAND memory chips. In the long run, weakened end markets like smartphones and automotive computing will come back strong when the COVID-19 crisis ends. Micron investors will remember 2020 as a speed bump on the road to fantastic long-term growth.

Micron CEO Sanjay Mehrotra explained the situation this way at an online industry conference last week: "5G will be a significant growth driver for multiple years in terms of increased unit sales as well as increased content for both DRAM and NAND. ... We are at the sweet spot of the growth cycle in data center, and data center is a long-term growth driver for the industry."

If you're not buying Micron at these low prices, you'll regret that decision in 2021 and beyond.

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Ultra Clean Holdings

If you like Micron Technology as a value investment, you'll love Ultra Clean Holdings (NASDAQ:UCTT) as well.

The maker of clean-room equipment used in the manufacturing process for all sorts of semiconductors is tapping into the same long-term trends as Micron. The COVID-19 crisis has barely registered as a hiccup in Ultra Clean's financial statements so far, though. This company adopted social distancing and remote-work policies far ahead of government orders, and a global network of equipment factories allowed Ultra Clean to work around local virus-related disruptions by rerouting work to other facilities. First-quarter sales rose 23% year over year, and management expects another solid showing in the second quarter with roughly 17% revenue growth.

"While we don't know exactly how things will unfold longer term, we see continued strong demand through the second quarter and are confident that our team will continue to perform at a high level," CEO Jim Scholhamer said in Ultra Clean's first-quarter earnings call. "Obviously, we've seen push-outs of smartphones but we do see kind of a buffer ... the quality investments in the server and other areas that are still continuing and need to continue. ... We're seeing some winners kind of buffer the lower-end projection."

All of that being said, Ultra Clean's stock is trading 8% lower in 2020. Share prices sit 28% below February's all-time highs, valued at 11 times forward earnings and 9.4 times free cash flows. That's another no-brainer buy right now.

Universal Display

Display technology developer Universal Display (NASDAQ:OLED) set its current all-time highs in September, backing down due to multiple pressures on the important smartphone market. Universal Display suffered slowdowns from the Chinese-American trade tensions, and then the COVID-19 crisis came along. The stock is now trading 32% below those all-time highs and 24% lower in 2020 alone. This is less of an obvious deep-discount value play than the other two tech tickers on my list, trading at 37 times forward earnings today.

It's also the most impressive long-term growth stock of the bunch:

MU Revenue (TTM) Chart

MU Revenue (TTM) data by YCharts

Organic light-emitting diode (OLED) screens have mostly been found in higher-end smartphones and really exclusive TV sets so far, but that's changing as Universal Display's screen-building clients ramp up improved manufacturing lines.

"You're starting to see some lower-cost smartphones. You're moving into the midrange and even low range," said CFO Sid Rosenblatt at another industry conference in May. "You've got the Honor 30, which is a $425 phone, and then you've got the Galaxy M21, which is a $200 phone, all of which have OLED screens. So as capacity grows, more manufacturers get into the market, obviously, costs come down."

The same mass-production progress is happening in the TV market, too.

"Last year, there were about 15 OEMs that used LG Display panels. And now they've added four more this year. So you've got VIZIO, Sharp, and Huawei all coming out with OLED TVs this year," Rosenblatt said. "The initial 55-inch OLED 4K or just high-definition TV was $3,600 a few years ago. Now you can get a 55-inch 4K OLED TV at Costco for about $1,200. So it is getting close to that price point."

OLED screens have been penetrating the mainstream market for years, and that process will continue. Come back in five years and you'll see big-screen OLED TVs in many homes, and the technology should evolve into a default choice for mass-market phones as well. Beyond that, Universal Display is developing power-sipping lighting panels to break into the general lighting market, and the company is also researching materials for parts of the OLED manufacturing stack that other companies have patented so far.

In other words, Universal Display could roughly double its revenues even if the global market for OLED panels doesn't grow any further -- and that market is most certainly going to expand for years to come. This stock can make you rich, even if you missed the torrential growth it posted over the last decade.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.