news digest ♦ Equipment and Materials
Disordered crystals: A replacement for classic nitrides?
The race is on to identify the band gap energy and carrier mobility of the new semiconductor ZnSnN2
Recently, the European Commission has flagged the supply of both gallium and indium as “at risk,” recommending that market conditions be closely monitored to avoid production bottlenecks.
Enter theorist Walter Lambrecht, who pointed out that there is an interesting family of semiconductors composed of zinc, silicon, germanium, tin and nitrogen which is analogous to the pervasive (Al,Ga,In) nitride family – and completely gallium and indium free.
Intriguingly, ZnSiN2 and ZnSnN2 fit into the category of what many are calling “earth abundant element semiconductors,” a reference to the relatively low crustal abundance of gallium and indium.
Ultraviolet band gap ZnSiN2 has been synthesised previously, but the lower-energy tin-based family member (critical for photovoltaics and visible wavelength devices) has only recently been reported. In 2013, three groups, each using a different technique, obtained crystalline samples of ZnSnN2. These were Case Western Reserve University, the California Institute of Technology, and the University at Buffalo.
The phenomenon occurs as the sub-lattice containing zinc and tin atoms is variously “scrambled” while the host material remains single crystalline. This could enable a radically new approach to band gap tuning for optoelectronic devices: through controlled disorder in a crystalline material via growth conditions, not alloying, as postulated three decades previously.
This work was conducted in conjunction with Steve Durbin at Western Michigan University and the University at Buffalo, David Scanlon at University College London and Tim Veal at the University of Liverpool.
The work is described in detail in the papers,
“ Growth, disorder, and physical properties of ZnSnN2,” by N. Feldberg et al in Applied Physics Letters,103, 042109 (2013). doi: 10.1063/1.4816438
and
“Growth of ZnSnN2 by Molecular Beam Epitaxy,” by N. Feldberg et al in Journal of Electronic
Materials.DOI: 10.1007/s11664-013-2962-8
Showa Denko boosts ammonia production capacity in China
The company is strengthening its supply of gases for LED semiconductor production
Showa Denko (SDK) has increased the production capacity for high-purity ammonia at its manufacturing subsidiary in Zhejiang Province, China, from 1,000 t/y to 2,000 t/y. The expanded facility started operation this month.
The race is now on to identify intrinsic properties such as band gap energy and carrier mobility of this new semiconductor. Surprisingly, the collaboration (Buffalo, London, and Liverpool) has observed experimental evidence for disorder-induced reduction of the band gap. This was predicted by density functional theory calculations to span from 1.1 to 2.1 eV.
150
www.compoundsemiconductor.net March 2014
Zhejiang Quzhou Juhua Showa Electronic Chemical Materials Co., Ltd. Site
High-purity ammonia is used for nitride film deposition
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