LEDs ♦ news digest
growth technology has minimised impurities to within industry acceptable limits.
The Australian-based firm says that the TEM report confirms an impressive microstructure with a defect density comparable to commercial MOCVD grown with a GaN underlying template. BluGlass reckons that its low defect density highly crystalline material grown at low temperature is a breakthrough, and is essential in demonstrating that its RPCVD method is commercially viable for LED chip growth. The firm believes its flexible RPCVD technology, because of its low temperature, offers manufacturers many potential benefits including higher efficiency, lower manufacturing costs and greater scalability. The superior material quality has been achieved partly due to reducing trace amounts of chemical impurities incorporated in GaN films during growth. In the past, BluGlass research has been limited by the presence of two impurities which were severely affecting material quality; oxygen and carbon.
Through hardware upgrades and process changes, oxygen impurities have been reduced to almost commercially acceptable levels and the firm says the material is no longer a hindrance to material quality. BluGlass says that carbon impurities are also being reduced towards industry acceptance with its new growth approach. BluGlass CEO, Giles Bourne comments, “These achievements demonstrate, for the first time, that high crystalline GaN films can be grown at low temperature using RPCVD. This is a critical step in proving to industry the potential of breakthrough technology. A low temperature commercial process would have been truly exciting implications for the LED industry. It has the potential to offer significant advantages for both device performance and low cost manufacturing.” The company is now focussing on tweaking the process to reduce the impurities to within industry accepted limits.
The successful reduction of these impurities should enable BluGlass to achieve, in the short term, two main milestones. The first is to produce films with properties similar to MOCVD grown films with industry accepted electrical properties. The company is also striving to improve device efficiency and confirm the competitive advantages of its RPCVD process. BluGlass believes that achieving these targets will lead to customer engagement and the placing of a demonstration tool with a leading LED manufacturer. A basic LED is composed of multiple semiconductor layers. Low defect density, or high crystalline quality, are critical in order to achieve the necessary device performance for commercial applications. Attaining a low defect density is vital in improving device performance. TEM images illustrating the low temperature RPCVD top GaN layer are shown below in Figures 1 and 2. BluGlass says the defect density is not generally higher than those observed in a typical underlying high temperature, commercial MOCVD GaN
template. BluGlass adds that this dramatic improvement for RPCVD is largely due to the reduction of impurities incorporated in the GaN layer during growth. As its technology team continues to further reduce impurities, BluGlass is aiming to file patents for its novel RPCVD technology in the near future.
GaAs back on track with
expanding RF wafer market But LEDs will rapidly lead the growth according to Yole Développement’s latest analysis
According to the new report “GaAs Wafer Market & Applications,” the GaAs wafer market should represent a business of over $650 million by 2017.
After the large recovery growth from 2009, the GaAs substrate market dramatically weakened in 2011 due to low demand for RF circuits, used in handsets and WLANs, and in optoelectronics, in particular, LEDs and laser diodes. With LEDs, there are now other substrates that companies are focussing on.
Apart from sapphire and gallium nitride, which are both very costly, silicon is the one to watch out for. Regarding power devices, silicon is also a main contender but on the whole, progress appears to be slow, particularly for 6” and 8” developement. Since the strong growth rate of over 22% achieved in 2010, the GaAs substrate market only increased by just over 4% in 2011, reaching a value of nearly $360 million.
April/May 2012
www.compoundsemiconductor.net 67
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120 |
Page 121 |
Page 122 |
Page 123 |
Page 124 |
Page 125 |
Page 126 |
Page 127 |
Page 128 |
Page 129 |
Page 130 |
Page 131 |
Page 132 |
Page 133 |
Page 134 |
Page 135 |
Page 136 |
Page 137 |
Page 138 |
Page 139 |
Page 140 |
Page 141 |
Page 142 |
Page 143 |
Page 144 |
Page 145 |
Page 146 |
Page 147 |
Page 148 |
Page 149 |
Page 150 |
Page 151 |
Page 152 |
Page 153 |
Page 154 |
Page 155 |
Page 156 |
Page 157 |
Page 158 |
Page 159 |
Page 160 |
Page 161 |
Page 162 |
Page 163 |
Page 164 |
Page 165 |
Page 166 |
Page 167 |
Page 168 |
Page 169 |
Page 170 |
Page 171 |
Page 172 |
Page 173 |
Page 174 |
Page 175