This page contains a Flash digital edition of a book.
News  Review


Osram’s InGaN LED chips on silicon in pilot stage


RESEARCHERS at Osram Opto Semiconductors have succeeded in manufacturing high performance prototypes of blue and white LEDs, in which the light-emitting GaN layers are grown on 150mm silicon wafers. The silicon replaces the sapphire substrates commonly used until now without a loss in quality. Already in the pilot stage, the new LED chips are to be tested under practical conditions, meaning that the first LEDs on silicon from Osram Opto could hit the market in just two years.


“Our investments in years of research are paying off, because we have succeeded in optimizing the quality of the gallium-nitride layers on the silicon substrates to the point where efficiency and brightness have reached competitive market levels. Stress tests demonstrate the high quality and durability of the LEDs,” says Peter Stauss, project manager at Osram Opto Semiconductors.


The company has acquired expertise over


the last 30 years in the epitaxy process, the foundation for this milestone in the development of new manufacturing technologies. The German Federal Ministry of Education and Research funds these activities as part of its “GaNonSi” project network. This is a pioneering development for several reasons. On account of its widespread use in the semiconductor industry, the availability of large wafer diameters and its very good thermal properties, silicon is an attractive and low- cost option for the lighting markets of the future.


Quality and performance data on the fabricated LED silicon chips match those of sapphire-based chips: the blue UX:3 chips in the standard Golden Dragon Plus package achieve a brightness of 634 mW at 3.15 volts, equivalent to 58 percent efficiency. These are outstanding values for 1 mm2 chips at 350 mA. In combination with a conventional phosphor converter in a standard housing – in other words as white LEDs – these prototypes


Global nitride LED revenues fall in 2011


AFTER 60% growth in 2010, the GaN LED market is expected to fall 6% in 2011 to $8.0 billion as reported in IMS Research’s latest “Quarterly GaN LED Supply/Demand Report”.


The decline can be attributed to a number of factors including a widening surplus resulting in significant pricing pressure. Supply grew nearly 3 times faster than demand from 2010 to 2011, resulting in depressed LED factory utilisation levels. The LED surplus rose from a relatively healthy 7% in 2010 to 45% in 2011 and is predicted to widen further in 2012.


With both panel shipments and LED penetration below expectations and average LED prices for backlighting declining 34% on a volume weighted average basis on depressed utilisation, backlighting revenues fell 13% to $4.8 billion. ASPs for certain backlighting markets were down as much as 45% in 2011.


As a result, backlighting fell from 64% of


2010 GaN LED revenues to 59% of 2011 GaN LED revenues and are likely to continue falling on a percentage basis in the future as backlight markets become saturated and the lighting market accelerates.


LED revenues for TVs are expected to fall 5% in 2011 to $1.9B as penetration is only expected to reach 39%, down from the previous estimate of 43%.


However, the GaN LED market is expected to recover, enjoying annual growth each year from 2012 to 2015 including double- digit growth in 2013 and 2014 as the lighting market accelerates.


The 2012 market is expected to grow 5%, but still remain below 2010 levels. Backlighting is expected to be flat on slower unit growth and price reductions, while lighting is expected to be up 30% as LED lamp penetration jumps as prices continue to fall. Lighting revenues are expected to overtake TV revenues for GaN LEDs in 2012, a year earlier than


6 www.compoundsemiconductor.net January/February 2012


previously predicted. This is a result of increasing LED lighting demand on lower pricing while reducing the LED outlook in TVs on lower penetration than previously predicted along with the use of low cost direct LED backlights in developing markets.


The low cost direct LED backlights use around half the LED die area as conventional edge backlights due to significantly reducing the brightness specification along with adopting a thicker form factor that allows wide viewing angle packages to be adopted which further reduces the number of LEDs required. While the adoption of these new low cost direct-type backlights will narrow the cost differential with CCFL LCD TVs, the thicker form factor and reduced brightness capability will narrow their appeal.


The lighting share of the GaN LED market is expected to surge from 21% in 2011 to 49% in 2016 with lighting LED revenues expected to grow more than 300% and units expected to grow in excess of 1500% over this period.


correspond to 140 lm at 350 mA with an efficiency of 127 lm/W at 4500 K.


“For these LEDs to become widely established in lighting, the components must get significantly cheaper while maintaining the same level of quality and performance,” Stauss emphasizes. “We are developing new methods along the entire technology chain for this purpose, from chip technology to production processes and housing technology.”


Mathematically speaking, it is already possible today to fabricate over 17,000 LED chips of one square millimetre in size on a 150 millimetre wafer. Researchers have already demonstrated the first structures on 200mm.


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  |  Page 176  |  Page 177  |  Page 178  |  Page 179  |  Page 180  |  Page 181  |  Page 182  |  Page 183  |  Page 184  |  Page 185  |  Page 186  |  Page 187  |  Page 188  |  Page 189  |  Page 190  |  Page 191  |  Page 192  |  Page 193  |  Page 194  |  Page 195  |  Page 196  |  Page 197  |  Page 198  |  Page 199  |  Page 200  |  Page 201  |  Page 202  |  Page 203  |  Page 204  |  Page 205  |  Page 206  |  Page 207  |  Page 208  |  Page 209  |  Page 210  |  Page 211  |  Page 212  |  Page 213  |  Page 214  |  Page 215  |  Page 216  |  Page 217  |  Page 218  |  Page 219  |  Page 220  |  Page 221  |  Page 222  |  Page 223  |  Page 224  |  Page 225  |  Page 226  |  Page 227  |  Page 228  |  Page 229  |  Page 230  |  Page 231  |  Page 232  |  Page 233  |  Page 234  |  Page 235  |  Page 236  |  Page 237  |  Page 238  |  Page 239  |  Page 240  |  Page 241