The term may have been coined back in 2015:
There are countless technology disciplines and startups comprising the “high-tech” world, but we needed a way to categorize startups in the life sciences, energy, clean technology, computer sciences, materials, and chemicals sectors. After many hours of debate among ourselves and others, we decided to use the term “deep technology” to build a new category of technology startups. - Swati Chaturvedi
There is somewhat of a wealth of different definitions. Sometimes people working on AI qualify as "deep", but sometimes they are "just" software. People building hardware (for instance, science-based startups) sometimes are hard tech.
The categorization may not be having the desired impact, since companies (and people) can be left outside investment, or visibility programs, just because of the labels that they (or others) attached to the companies.
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