如何在孔洞型光子晶体中填充材料

光子晶体在半导体光电子器件里边使用的非常多。也有好多研究者尝试在氮化镓基LED芯片里边引入光子晶体结构,来改善光的抽取。

贵金属的等离子效应,一直是纳米光子学研究的比较多的一个话题。很多研究者使用它来增强拉曼散射提升分子检测的灵敏度。也有研究者在LED芯片里边引入贵金属,使贵金属与LED芯片的量子阱耦合,以期待进一步的提升量子阱的量子效率。

分享一段小程序,在光子晶体孔洞里边填充贵金属的。里边假定填充的金属会在孔洞形成一个斜面。

但是,在实际的微纳米加工里边,可能会是怎样的形貌,很难预测。在孔洞里填充的金属薄膜之形貌,可能会由如下几个因素决定:
(1) 孔洞的直径大小;
(2) 蒸发台金属蒸发的速率;
(3) 蒸发台腔体的气压;
(4) 衬底的温度;
(5) 蒸发气态金属入射衬底的角度。

如果实验室有条件,可以尝试调整不同的工艺条件来制作样品 。然后,使用FIB将圆柱形的孔洞从顶部到底部切开,在SEM里边,转换不同的角度,来观测填充金属的形貌。

几何建模代码分享如下:

  1. deleteall; # Clear everything in the view;

  2. clear; # Clear all the variables in the workspace;

  3. Create a cylinder with an inclined plane

  4. R =2e-6; # Radius of the cylinder;

  5. h1=0.5e-6; # Height of the low point (R,0,h1) on the inclined plane;

  6. h2=2e-6; # Height of the up point (-R,0,h2) on the inclined plane;

  7. N=150; # Number of vector;

  8. #theta=linspace(0,2*pi,N); # theta vector;

  9. #x=R*cos(theta);

  10. #y=R*sin(theta);

  11. x=linspace(-R,R,N);

  12. y=linspace(-R,R,N);

  13. X=meshgridx(x,y);

  14. Y=meshgridy(x,y);

  15. Z=zeros(N,N);

  16. Equation for discribing the inclined plane;

  17. #Z=-(h2-h1)/2/R*X+(h1+h2)/2; # Points on the inclined plane;

  18. Only the points on the inclined plane whose projection on XY plane within a circle ® will be kept

  19. otherwise, the height will be assigned 0.

  20. for (i=1:N)

  21. {for (j=1:N)

  22. {if (X(i,j)^2+Y(i,j)^2<=R^2) # Control condition
    
  23.     {Z(i,j)=-(h2-h1)/2/R*X(i,j)+(h1+h2)/2;} 
    
  24.     }
    
  25.     }
    
  26. addimport;

  27. set(“name”,“inclinedcylinder”);

  28. importsurface2(Z,x,y,1);

  29. set(“z min”,0);

  30. set(“material”,“etch”);

  31. addtogroup(“Hole”);

  32. addcircle;

  33. set(“radius”,R);

  34. set(“z min”,0);

  35. set(“z max”,h2);

  36. set(“material”,“Ag (Silver) - CRC”);

  37. set(“override mesh order from material database”,2);

  38. addtogroup(“Hole”);

  39. Create holes array

  40. Nx=10;

  41. Ny=10;

  42. d=3*R; # The distance between each circle, centre to centre distance;

  43. selectall;

  44. for (i=1:Nx)

  45. {for (j=1:Ny)

  46. {copy(0,0);
    
  47.  set("x",(i-1)*d);
    
  48.  set("y",(j-1)*d);}
    
  49. }
    
  50. selectall;

  51. move(-Nxd/2+R,-Nyd/2+R);

  52. Before creating GaN layer, add GaN material into the database at first.

  53. cd(“E:\Lumerical\Literatures\Materials_database-2019-02-11\database\data\main\GaN”);

  54. data=readdata(“Kawashima.txt”);

  55. sigma=matrix(length(data(:,1)),2);

  56. sigma=[c/data(:,1)*1e6,(data(:,2)+sqrt(-1)*data(:,3))^2];

  57. temp=addmaterial(“Sampled 3D data”);

  58. setmaterial(temp,“name”,“GaN”);

  59. setmaterial(“GaN”,“anisotropy”,0);

  60. setmaterial(“GaN”,“sampled data”,sigma);

  61. Create substrate

  62. Lx=Nxd+2R;

  63. Ly=Nyd+2R;

  64. addrect;

  65. set(“z min”,-5*h2);

  66. set(“z max”,h2);

  67. set(“x”,0);

  68. set(“y”,0);

  69. set(“x span”,Lx);

  70. set(“y span”,Ly);

  71. set(“name”,“GaN”);

  72. set(“material”,“GaN”);

  73. set(“override mesh order from material database”,3);

inclinedplane
两张对应的图片,可以看到周期排列的微孔阵列,以及孔内的斜面

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