Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10H—INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
  • H10H20/00—Individual inorganic light-emitting semiconductor devices having potential barriers, e.g. light-emitting diodes [LED]
  • H10H20/80—Constructional details
  • H10H20/85—Packages
  • H10H20/855—Optical field-shaping means, e.g. lenses
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/28—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
  • H01L2924/0001—Technical content checked by a classifier
  • H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10H—INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
  • H10H20/00—Individual inorganic light-emitting semiconductor devices having potential barriers, e.g. light-emitting diodes [LED]
  • H10H20/80—Constructional details
  • H10H20/85—Packages
  • H10H20/855—Optical field-shaping means, e.g. lenses
  • H10H20/856—Reflecting means
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10H—INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
  • H10H20/00—Individual inorganic light-emitting semiconductor devices having potential barriers, e.g. light-emitting diodes [LED]
  • H10H20/80—Constructional details
  • H10H20/882—Scattering means

Definitions

• the invention relates to a semiconductor device which emits polarized radiation having a first polarization direction.
• Radiation emitting semiconductor devices such as light emitting diodes are advantageous light sources because of their compact size and efficiency.
• the generated radiation due to spontaneous emission is mostly unpolarized.
• applications such as the LCD backlight require polarized radiation.
• the radiation generated by the light emitting diodes is due to an external downstream of the light emitting diodes
• Polarization filter polarized. But this is contrary to a compact design. In addition, these systems typically lose the non-transmitted radiation, that is, they are no longer used in the system, which suffers the efficiency of the system.
• An object to be solved in the present case is to specify a semiconductor component which generates polarized radiation in an efficient manner. This object is achieved by a polarized radiation-emitting semiconductor component according to claim 1. Advantageous developments of the semiconductor device are given in the dependent claims.
• the semiconductor device which emits polarized radiation having a first polarization direction, a chip housing, a semiconductor chip which is arranged in the chip housing and generates unpolarized radiation, and a chip-removed, integrated in the chip housing polarization filter, the semiconductor chip is subordinate in a preferred direction and divides the radiation emitted by the semiconductor chip into a first radiation component with the first polarization direction and a second radiation component with a second polarization direction, the chip-distant polarization filter having a higher transmittance for the first radiation component than for the second Radiation component.
• the first radiation component is predominantly transmitted through the chip-distant polarization filter, while the second radiation component is largely reflected at the chip-distant polarization filter.
• the reflected second radiation component returns to the chip housing after the reflection on the chip-distant polarization filter. Reflection processes can take place there, or absorption and reemission processes can occur in the semiconductor chip, which lead to a recovery of the reflected second radiation component. In the course of these processes, a change of the polarization direction is possible, so that a part of the reflected second radiation component then has the first polarization direction.
• a light beam thus ideally runs in the semiconductor component or in the chip housing until it impinges on the polarization filter with the first polarization direction and can decouple. Or the light beam is absorbed by the semiconductor chip and re-emitted with the first polarization direction and can thus decouple.
• a near-chip polarization filter is arranged on a surface of the semiconductor chip facing away from the chip-distant polarization filter, the chip-near polarization filter having a higher transmittance for the first radiation fraction than for the second radiation fraction.
• Polarization filter is transmitted through, while the second portion of radiation at the chip near polarization filter is largely reflected back into the semiconductor chip and can be recovered there by absorption and reemission.
• the transmitted radiation component strikes the chip-distant polarization filter, where it is filtered, whereby the same processes as described above can proceed.
• the semiconductor device in this embodiment can emit more polarized radiation than in the embodiments with only one polarization filter.
• the production is more complex, since the smaller chip-near polarizing filter is more difficult to produce than the chip-distant larger polarization filter.
• chipfern is meant here that the polarization filter is not directly adjacent to the semiconductor chip. Accordingly, “close to the chip” means that the polarization filter is adjacent to the semiconductor chip.
• the semiconductor chip is in particular made of a
• Layer stack of epitaxially grown semiconductor layers formed, wherein the layer stack has an active zone for generating radiation of wavelength ⁇ .
• the active zone comprises a radiation-generating pn junction.
• this pn junction can be formed by means of a p-type and an n-type semiconductor layer, which adjoin one another directly.
• the actual radiation-generating layer for example in the form of a doped or undoped quantum layer, to be arranged between the p-type and the n-type semiconductor layer.
• the quantum layer can be designed as a single quantum well structure (SQW, single quantum well) or multiple quantum well structure (MQW, multiple quantum well) or else as a quantum wire or quantum dot structure.
• the layer stack of the semiconductor chip contains a nitride compound semiconductor, that is to say the layer stack has Al x Ga 7 Ini_x- y N, where O ⁇ x ⁇ l, 0 ⁇ y ⁇ 1 and x + y ⁇ 1 this material does not necessarily have a mathematically exact composition according to the above formula. Rather, it can contain one or more dopants and additional constituents. Have parts that do not change the characteristic physical properties of the Al x Ga y Ini_ x - y N material substantially. For the sake of simplicity, however, the above formula contains only the essential constituents of the crystal lattice (Al, Ga, In, N), even if these may be partially replaced by small amounts of other substances.
• the chip-distant and / or chip-near polarization filter can, according to a preferred embodiment, have a metal grid.
• the metal grid is formed of metal strips that run parallel to each other. Light rays having a direction of polarization parallel to the metal strips are thereby reflected, while light rays having a polarization direction perpendicular to the metal strips are transmitted.
• the first polarization direction corresponds to the polarization direction perpendicular to the metal strips and the second polarization direction corresponds to the polarization direction parallel to the metal strips.
• first polarization direction correspond to the parallel polarization direction
• second polarization direction correspond to the perpendicular polarization direction
• the metal strips of the metal grid are preferably arranged at a distance which is smaller than the wavelength ⁇ .
• the width of the metal strips should be a fraction of this distance.
• Such small structures can be made, for example, by lithographic techniques or an imprinting process.
• the metal strips can be applied directly to the surface of the semiconductor chip.
• the chip-distant polarizing filter it is conceivable to apply the metal strips to a carrier, for example a plastic film or a glass substrate, and to fix this to the chip housing.
• birefringent multilayer filter Another realization of a polarization filter is given by a birefringent multilayer filter. This has in particular at least one first birefringent
• the second layer of the first layer is arranged downstream in the emission direction.
• the first and the second layer have an optical thickness of ⁇ / 4.
• the birefringent property of the layers can be produced, for example, by stressing the layers.
• the layers can be pulled in a certain direction.
• the layers contain a plastic material.
• the polarization filter is a film containing in particular a plastic material.
• the film is easy to handle and can be easily integrated into the chip housing.
• the chip housing has a recess, which is delimited by a bottom surface on which the semiconductor chip is mounted, and at least one side surface.
• at least the side surface reflective, ie it has an advantageous high reflectance.
• the floor surface may be reflective. Due to the advantageously high degree of reflection, a large part of the second radiation component reflected on the chip-distant polarization filter can be recovered, that is to say a part of the reflected second radiation component can change and decouple the polarization direction by reflections in the chip housing or absorption and reemission processes in the semiconductor chip.
• a symmetrical shape for example a rotationally symmetric or rotationally symmetrical shape, of the recess is advantageous.
• suitable multi-planar reflections can occur to change the direction of polarization.
• more than two reflections on the chip housing are favorable in order to achieve a change in the polarization direction.
• the side surface is at least partially covered by a reflective layer.
• the bottom surface may be at least partially covered by a reflective layer.
• the reflection layer is a metal layer. By means of a metal layer, a comparatively high degree of reflection can be achieved.
• the side surface may be smooth, that is to say it has only roughness structures small with respect to the wavelength ⁇ .
• reflective reflection can take place, that is to say the angle of incidence of an incident light beam and the angle of reflection are the same, based on the incidence solder.
• the side surface has unevenness that is large in relation to the wavelength ⁇ .
• the side surface is roughened by means of the unevenness in such a way that smooth partial surfaces running obliquely to each other develop, which act as mirror surfaces.
• the side surface therefore preferably has a surface structure which is formed from obliquely mutually smooth surfaces, which act as mirror surfaces.
• a polarization mixing of the second radiation component reflected on the chip-distant polarization filter can be improved by such a surface structure.
• the chip-remote polarization filter covers the recess.
• the chip-remote polarization filter can be arranged on the chip housing for this purpose.
• the polarizing filter can either rest on the chip housing and cover the recess or be arranged precisely in the recess, for example on a filling mass.
• the polarizing filter can serve as a cover which protects the semiconductor chip from external influences, for example. Both by the arrangement of the chip remote polarization filter on the chip housing and by the arrangement in the recess of the polarization filter is integrated into the chip housing.
• a filling compound can be arranged in the recess between the chip-distant polarization filter and the semiconductor chip.
• the filling material completely fills the recess.
• a filling compound is used to protect the semiconductor chip from external influences such as the ingress of moisture, dust, foreign bodies, water, etc.
• the filling compound may have a filling material which contains an epoxy resin or a silicone.
• a filling material which contains an epoxy resin or a silicone.
• the refractive index jump between the semiconductor chip and the surroundings can furthermore be reduced so that lower radiation losses due to total reflections occur at the transition between the semiconductor chip and the surroundings.
• the surface of the filling compound can form a suitable support surface for the polarizing filter.
• the layer stack is first grown epitaxially on a growth substrate. Then, a support is applied to a surface of the layer stack opposite to the growth substrate, and subsequently the growth substrate is separated.
• the growth substrates used for nitride compound semiconductors such as SiC, sapphire or GaN, are comparatively expensive, this method offers the particular advantage that the growth substrate is recyclable.
• the thin-film semiconductor chip is a Lambertian radiator with advantageously increased coupling-out efficiency.
• FIG. 1 shows a schematic cross-sectional view of a first exemplary embodiment of a semiconductor component according to the invention
• FIG. 2 shows a schematic cross-sectional view of a second exemplary embodiment of a semiconductor component according to the invention
• FIG. 3 shows a schematic cross-sectional view of a third exemplary embodiment of a semiconductor component according to the invention
• Figure 4 is an illustration of multiple reflections on mirror surfaces.
• the semiconductor component 1 shown in FIG. 1 has a chip housing 2 and a semiconductor chip 3, which is arranged in the chip housing 2.
• a chip remote polarization filter 4 is arranged, which covers a recess 5 of the chip housing 2.
• the chip-distant polarization filter 4 is integrated into the chip housing 2.
• the polarizing filter 4 has a metal grid consisting of metal strips 4a which are parallel to each other.
• the semiconductor chip 3 is arranged in the recess 5 of the chip housing 2.
• the semiconductor chip 3 is in a
• the filling compound contains in particular a radiation permeable filling material.
• the filler may be a silicone or an epoxy resin.
• the recess 5 is bounded by an inner side surface 6 and an inner bottom surface 7 of the chip housing 2.
• the recess 5 has a rotationally symmetrical shape, namely the shape of a truncated cone tapering in the direction of the semiconductor chip 3.
• the side surface 6 thus corresponds to the lateral surface of a truncated cone.
• the rotational symmetry exists with respect to a preferred direction V.
• the recess 5 can also be provided with a rotationally symmetrical shape, so that the recess 5 has more than one side surface 6.
• the preferred direction V is at the same time the direction in which a large part of the radiation coming from the semiconductor component 1 is emitted.
• the side surface 6 is reflective and therefore serves as a reflector.
• the bottom surface 7 may be reflective and together with the side surface 6 form the reflector.
• the side surface 6 may be covered with a reflection layer 11.
• a metal layer is suitable for this purpose.
• the side surface 6 is smooth, that is, it has only roughness structures that are small compared to the wavelength ⁇ .
• reflective reflection can take place, that is to say the angle of incidence of an incident light beam and the angle of reflection are the same, based on the incidence solder.
• the semiconductor chip 3, which is in particular a thin-film semiconductor chip, generates unpolarized radiation S, which impinges on the polarization filter 4 in the preferred direction V.
• the polarization filter 4 divides the unpolarized radiation S into a first radiation component S1 having a first polarization direction and a second radiation component S2 having a second polarization direction, the chip-distant polarization filter 4 having a higher transmittance for the first radiation component S1 than for the second radiation component S2.
• the first radiation component S1 is therefore predominantly transmitted, while the second radiation component S2 is largely reflected.
• the semiconductor component 1 emits altogether polarized radiation with the first polarization direction.
• the reflected second radiation component S2 passes back into the chip housing 2 after the reflection on the chip-distant polarization filter 4. There, reflection processes can take place, or absorption and reemission processes can occur in the semiconductor chip 3. In the course of these processes, a change in the polarization direction is possible, so that a part of the reflected second radiation component S2 then has the first polarization direction and can be coupled out of the semiconductor component 1.
• the light beam can then decouple from the semiconductor device 1.
• the light beam can also be absorbed by the semiconductor chip 3 and re-emitted with the first polarization direction and coupled therewith (not shown).
• the polarizing filter 4 has a metal grid. Light beams which have a polarization direction parallel to the metal strips 4a are in this case reflected, while light beams having a polarization direction perpendicular to the metal strips 4a are transmitted. In this case, therefore, the first polarization direction corresponds to the polarization direction perpendicular to the metal strips 4a and the second polarization direction corresponds to the polarization direction parallel to the metal strips 4a.
• the efficiency of the present semiconductor device 1 is compared with a conventional optical system using an external polarizing filter.
• the semiconductor chip 3 has a diffuse reflectance of 50% and a size of 0.5mm x 0.5mm x 0.2mm.
• For the filling mass is a refractive index of 1.5.
• the diameter of the bottom surface 7 is 1.8 mm and the diameter of the recess 5 on the radiation exit side is 3 mm.
• the chip housing 2 has an average height of about 1.5 mm.
• the transmittance of the polarizing filter 4 is 50%.
• the semiconductor component 1 illustrated in FIG. 2 has essentially the same structure as the semiconductor component 1 of FIG. 1. The difference lies only in the surface structure of the side surface 6.
• the side surface 6 has unevennesses 8, which are large in relation to the wavelength ⁇ .
• the side surface 6 is roughened by means of the unevenness 8 in such a way that smooth partial surfaces 9 running obliquely to each other develop, which act as mirror surfaces.
• the side surface 6 thus has a surface structure which is formed from obliquely extending smooth partial surfaces 9, which act as mirror surfaces.
• a decoupling efficiency of about 44.6% can be achieved, which is thus below the achievable in the first embodiment Auskoppeleffizienz of about 52%.
• a polarization mixing of the second radiation component S2 reflected on the chip-distant polarization filter 4 can be improved by such unevennesses 8.
• a side surface with unevenness as in the second embodiment seems to have a positive effect, since the recoverability achievable efficiency increase in the second embodiment is about 28% and thus almost the same size as in the first embodiment with 29%.
• FIG. 3 shows a further embodiment of a semiconductor component 1 according to the invention.
• This semiconductor component 1 is essentially constructed like the semiconductor component 1 of FIG.
• the semiconductor component 1 shown in FIG. 3 additionally has a chip-near polarization filter 4.
• the near-chip polarization filter 4 as well as the chip-distant polarization 4 has a metal grid with metal strips 4a running parallel to one another.
• the chip near polarization filter 4 functions in the same way as the chip distant polarization filter 4.
• the metal strips 4a may be applied directly to the surface of the semiconductor chip.
• the use of a foil which has the metal strips 4a is advantageous.
• the film is arranged on the chip housing 2 and can be glued, for example.
• a first filtering may already take place by means of the chip-near polarization filter 4, wherein preferably the first radiation component is predominantly transmitted through the chip-near polarization filter 4, while the second radiation component is largely reflected by the chip-near polarization filter 4 (not shown).
• the through the chip-near polarizing filter 4 transmitted radiation ⁇ tion proportion is filtered again by the chip-distant polarization filter 4 in the manner already described.
• the semiconductor device 1 in this embodiment can emit more polarized radiation than in the embodiments with only one polarization filter. However, the production is more complex, since the smaller chip-near polarizing filter 4 is more difficult to produce than the chip-distant larger polarization filter. 4
• the polarizing filters 4 of the embodiments illustrated in FIGS. 1 to 3 do not have to have a metal grid.
• the polarizing filters 4 can also be, for example, birefringent multilayer filters or other types of polarization filters.
• FIG. 4 illustrates in the left-hand illustration the case in which two light beams L1 and L2 in the chip housing are reflected on two mirror surfaces R1 and R2, which may belong to the side surface, for example.
• the polarization direction does not change: the polarization directions of the incident and outgoing light beams Ll and L2 are parallel to each other.
• L2 are perpendicular to each other.
• the invention is not limited by the description with reference to the embodiments. Rather, the invention encompasses any novel feature as well as any combination of features, including in particular any combination of features in the claims, even if this feature or combination itself is not explicitly stated in the patent claims or exemplary embodiments.

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• 2007
  • 2007-12-14 DE DE102007060202A patent/DE102007060202A1/de not_active Withdrawn
• 2008
  • 2008-12-12 EP EP08863055A patent/EP2232593A2/de not_active Withdrawn
  • 2008-12-12 TW TW097148491A patent/TW200937686A/zh unknown
  • 2008-12-12 KR KR1020107015622A patent/KR20100098700A/ko not_active Withdrawn
  • 2008-12-12 CN CN2008801203951A patent/CN101897044B/zh not_active Expired - Fee Related
  • 2008-12-12 US US12/747,091 patent/US20100295076A1/en not_active Abandoned
  • 2008-12-12 WO PCT/DE2008/002079 patent/WO2009076939A2/de not_active Ceased
  • 2008-12-12 JP JP2010537253A patent/JP2011507240A/ja active Pending

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