Patterned Sapphire Substrates (PSS) for UV LEDs

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Patterned Sapphire Substrates

We, along with our partners, can fullfill all your PSS needs.

Using Patterned Sapphire Substrates can significantly increase the light output of LEDs. Benefits include:

- Increased light emissions of active quantum well layers as the result of reduced epitaxial defect density.

-PSS reduces light loss due to the Total Internal Reflection (TIR) phenomena by enabling a photon scattering effect.

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Patterned Sapphire Substrate for Ultraviolet (UV) LEDs

Researchers have used several types of sapphrie wafer including:

  • Flat (FSS)
  • Patterned (PSS)
  • Silica Array (PSSA)

To make Ultraviolet (UV) Light Emitting Diodes (LEDs).

Patterned Sapphire Wafers for R&D

The other important driver for sapphire is its use in semiconductor production for the aerospace and defense industries. The way in which the market is divided is subdivided - subdivided, based on its wafer - subdivided size. A very important sector for this is aerospace, which is divided into thin, high-performance, transparent and ultra-thin layers because of its transparent armour. [Sources: 7]

As mentioned above, the density of the edge dislocation decreases with the growth of the GaN layer, resulting in a reduced FWHM value of 102%. This effect is interpreted as the result of the compressed hydrostatic load on the component, which the thin Ga N layer undergoes. When cultivated in sapphire with an aln buffer layer, lead generally dissolves to about 2% and lead to about 0.5%. [Sources: 2, 5, 8]

Figure 2 illustrates the effect of planar sapphire lead on the FWHM of the GaN layer and the density of the edge contortions. Figure 5 shows the effects of the formation of a thin Ga N layer with an Aln buffer layer of about 1.5%. [Sources: 5]

The effect of planar sapphire lead on the half-life of the GaN layer and the density of the edge contortions of a thin Aln buffer layer. [Sources: 5]

In addition to increasing apparent light output, a number of manufacturers claim that epitaxial layers on patterned substrates are more efficient than those grown on bare sapphire substrates. The FWHM value of LEDs with pss is lower than that of LEDs on sapphire substrates, suggesting that crystal quality is significantly improved by using PSS. The high EL intensity increases by 91% compared to LEDs on planar spheres and by more than 100% in planars. [Sources: 4, 5]

The larger diameter of sapphire wafers has the potential to make the manufacturing process significantly more efficient, but also presents challenges for manufacturers. For example, the cost of a 2-inch GaN wafer is about twice as high as for an 8-inch Ga-N wafer. Given the high cost of high-temperature wet etching, LED manufacturers and sapphire wafer suppliers need to seriously consider this, especially given the significant cost difference between the two substrate types. [Sources: 0, 7]

If demand for patterned sapphire substrates continues, it may ultimately be helpful for Sapshire to use other high-temperature wet etching technologies, as existing materials other than Sapshire have an established supply chain. The sapphire technology market and the growth of this technology are further segments, divided into two major segments: the semiconductor industry and the consumer electronics industry. This report is divided by industry into semiconductors, photovoltaics, electronics, automotive, medical devices and other industries. [Sources: 1, 7]

In the last 18 months of the program, we investigated the use of a specially developed sapphire substrate patterned with C-tarpaulins. The epitaxial structure of the LED is a contrast sample used by conventional sapphire substrates (CSS) using low pressure MOCVD. LEDs (light-emitting diodes) and nitride - based LEDs growing on a structuring saPPHIRE substrate (Fig. 2). [Sources: 0, 3, 6, 9]

A photoresist array was used as mask layer to transfer the sapphire pattern by applying an inductively coupled plasma reactive ion etching system using reactive Cl 2 gas. The membrane was turned upside down in a steel bracket and manually peeled off the SAPPHIRE substrate. A thick PDMS top layer was covered with a centrifugal layer and applied to a thin layer of C-tarpaulins (1.5 mm thick). [Sources: 3, 8]

This process is similar to that used in the silicon industry to produce the wafers used as substrates. This process makes the use of high temperature, high pressure and high temperatures, which are standard today, superfluous. [Sources: 4, 8]

According to the literature [16], the use of patterned sapphire substrates would effectively reduce the contortion of the filaments. Defects related to the degradation of electrical power, such as defects in the electrical conductivity of the wafers, are rarely investigated. [Sources: 5]

This article proposes a method to reduce the impact of bat ejection on patterned sapphire substrates by selecting the appropriate wavelength measurements. Atomic force microscopy (AFM) offers the possibility to study force - microscopy in a variety of materials such as lead, copper, gold and silver. This method can be used in many applications, for example, in chemical reaction analysis [16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 104, 105, 106, 111, 112, 113, 114, 115, 116, 12 Atomic force microscopy offers the possibility to analyze the sapphire substrate before epitaxial film growth. In addition, the pattern and PSS techniques are suitable for GaN epilayers that achieve high crystal quality in a single, continuous growth process. [Sources: 3, 6, 10]

 

 

Sources:

[0]: https://www.imtecacculine.com/sapphire_pss_wafer_etch_wet_vs_dry.html

[1]: https://compoundsemiconductor.net/article/91564/Rubicon_reveals_sapphire_plans/feature

[2]: https://www.nature.com/articles/srep03201

[3]: https://www.hindawi.com/journals/ijp/2014/796253/

[4]: https://sst.semiconductor-digest.com/2015/11/the-use-of-sapphire-in-mobile-device-and-led-industries-part-2/

[5]: https://cyberleninka.org/article/n/1182219

[6]: https://www.spiedigitallibrary.org/conference-proceedings-of-spie/9960/1/Reduction-of-batwing-effect-in-white-light-interferometry-for-measurement/10.1117/12.2236874.full

[7]: https://www.marketsandmarkets.com/Market-Reports/sapphire-semiconductors-market-391455.html

[8]: https://www.science.gov/topicpages/m/m-plane+sapphire+substrates

[9]: https://www.osti.gov/servlets/purl/1238367

[10]: https://parksystems.com/applications/electrical-electronics/display/156-surface-topography-considerations-of-patterned-sapphire-substrates-for-blue-green-light-emitting-diode

 

Below is just an example of PSS that we sell.

2" PSS with the following pattern specifications:

Pattern Pitch 3.0um ± 0.15um
Pattern Bottom 2.7um ± 0.15um
Pattern Space 0.3um ± 0.15um
Pattern Height 1.7um ± 0.15um

Patterned Sapphire Substrates